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Unit 4

Tax and Tip

Proportional Relationships and Percentages

Lesson 10

Expressions and Equations

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Let’s learn about sales tax and tips.

Unit 4 ● Lesson 10

Learning

Goal

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The Price of Sunglasses

Unit 4 ● Lesson 10 ● Activity 1

You are on vacation and want to buy a pair of sunglasses for $10 or less. You find a pair with a price tag of $10. The cashier says the total cost will be $10.45.

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What do you notice? What do you wonder?

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Warm-up: Notice and Wonder

Slides are CC BY NC Kendall Hunt Publishing. Curriculum excerpts are CC BY Open Up Resources, with adaptations CC BY Illustrative Mathematics.

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The Price of Sunglasses

Unit 4 ● Lesson 10 ● Activity 1

  • How much sales tax is being collected on the $10 sunglasses?
  • 45 cents is what percentage of $10?
  • What is the sales tax rate for our local area?

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Warm-up

Slides are CC BY NC Kendall Hunt Publishing. Curriculum excerpts are CC BY Open Up Resources, with adaptations CC BY Illustrative Mathematics.

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Shopping in Two Different Cities

Unit 4 ● Lesson 10 ● Activity 2

Different cities have different sales tax rates. Here are the sales tax charges on the same items in two different cities. Complete the tables.

City 1 City 2

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Slides are CC BY NC Kendall Hunt Publishing. Curriculum excerpts are CC BY Open Up Resources, with adaptations CC BY Illustrative Mathematics.

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Shopping in a Third City

Unit 4 ● Lesson 10 ● Activity 3

Here is the sales tax on the same items in City 3.

  1. What is the tax rate in this city?
  2. For the sales tax on the laundry soap, Kiran says it should be $0.84. Lin says it should be $0.87. Do you agree with either of them? Explain your reasoning.

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Slides are CC BY NC Kendall Hunt Publishing. Curriculum excerpts are CC BY Open Up Resources, with adaptations CC BY Illustrative Mathematics.

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Shopping in a Third City

Unit 4 ● Lesson 10 ● Activity 3

  • How did you determine the tax rates for the items in City 1 and City 2 from the previous activity?
  • How did determining the tax rate for City 3 differ from the work you did for the other cities?

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Slides are CC BY NC Kendall Hunt Publishing. Curriculum excerpts are CC BY Open Up Resources, with adaptations CC BY Illustrative Mathematics.

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Dining at a Restaurant

Unit 4 ● Lesson 10 ● Activity 4

  1. Jada has a meal in a restaurant. She adds up the prices listed on the menu for everything they ordered and gets a subtotal of $42.00.
    1. When the check comes, it says they also need to pay $3.99 in sales tax. What percentage of the subtotal is the sales tax?
    2. After tax, the total is $45.99. What percentage of the subtotal is the total?
    3. They actually pay $52.99. The additional $7 is a tip for the server. What percentage of the subtotal is the tip?

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Slides are CC BY NC Kendall Hunt Publishing. Curriculum excerpts are CC BY Open Up Resources, with adaptations CC BY Illustrative Mathematics.

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Dining at a Restaurant

Unit 4 ● Lesson 10 ● Activity 4

  1. The tax rate at this restaurant is 9.5%.

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One person’s subtotal is $24.95. Another person’s sales tax is $1.61.�How much will their sales tax be? How much was their subtotal?

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Slides are CC BY NC Kendall Hunt Publishing. Curriculum excerpts are CC BY Open Up Resources, with adaptations CC BY Illustrative Mathematics.

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Dining at a Restaurant

Unit 4 ● Lesson 10 ● Activity 4

  • How we might use an equation to solve the problem?
  • What are the two quantities being used in these problems?

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Slides are CC BY NC Kendall Hunt Publishing. Curriculum excerpts are CC BY Open Up Resources, with adaptations CC BY Illustrative Mathematics.

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Tax and Tip

Unit 4 ● Lesson 10

  • Where did we see and use fractional percentages in this lesson?
  • What are strategies we can use to calculate fractional percentages (including sales tax)?

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Lesson Synthesis

Slides are CC BY NC Kendall Hunt Publishing. Curriculum excerpts are CC BY Open Up Resources, with adaptations CC BY Illustrative Mathematics.

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Unit 4 ● Lesson 10

I understand and can solve problems about sales tax and tip.

Learning

Targets

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A Restaurant in a Different City

Unit 4 ● Lesson 10 ● Activity 5

At a dinner, the meal cost $22 and a sales tax of $1.87 was added to the bill.

  1. How much would the sales tax be on a $66 meal?
  2. What is the tax rate for meals in this city?

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Cool-down

Slides are CC BY NC Kendall Hunt Publishing. Curriculum excerpts are CC BY Open Up Resources, with adaptations CC BY Illustrative Mathematics.

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This slide deck is copyright 2020 by Kendall Hunt Publishing, https://im.kendallhunt.com/, and is licensed under the Creative Commons Attribution-NonCommercial 4.0 International License (CC BY-NC 4.0), https://creativecommons.org/licenses/by-nc/4.0/.

All curriculum excerpts are under the following licenses:

IM 6–8 Math was originally developed by Open Up Resources and authored by Illustrative Mathematics, and is copyright 2017-2019 by Open Up Resources. It is licensed under the Creative Commons Attribution 4.0 International License (CC BY 4.0). OUR's 6–8 Math Curriculum is available at https://openupresources.org/math-curriculum/.

Adaptations and updates to IM 6–8 Math are copyright 2019 by Illustrative Mathematics, and are licensed under the Creative Commons Attribution 4.0 International License (CC BY 4.0).

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Adaptations to add additional English language learner supports are copyright 2019 by Open Up Resources, and are licensed under the Creative Commons Attribution 4.0 International License (CC BY 4.0).

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The Illustrative Mathematics name and logo are not subject to the Creative Commons license and may not be used without the prior and express written consent of Illustrative Mathematics.

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