Word Problems
Ram is 8 more than twice the age of Rahim.
Ram
Rahim
Find their present ages.
x
y
x
=
+
2y
is / was
=
More/Greater /Exceeds
+ (after leaving some space).
Less/Smaller
- (after leaving some space).
Sum of two numbers
x + y
Difference of two numbers
x - y
Twice / thrice…..
Multiplication
Rules
Formulae / Properties.
Dividend = Divisor x Quotient + Remainder.
Perimeter of a triangle = sum of all the three sides.
Sum of the measures of the angles of a triangle = 180°
Perimeter of a rectangle = 2 ( l + b)
Speed = Distance / Time
8
Let us convert this statement into a Mathematical equation
Find the ages of Ram and Rahim
There are 2 unknowns
Assume one of the unknowns as x and other unknown as y
To form equations lets follow some rules, formulae and properties
Using these rules we will convert the given statement into mathematical form
Q. Form the pair of linear equations for the following problems and find their solution by substitution method.
Soln.
x
=
18
+
y
... (i)
According to the first condition,
According to the second condition
... (ii)
(ii) The larger of two supplementary angles exceeds the smaller by 18 degrees. Find them.
Let the larger angle be xo and the smaller angle be y
180
+
x
=
y
∴ The measures of the angles are 81o and 99o.
To find the two angles i.e. the larger angle and the smaller angle
What are we suppose to find ?
Exceeds
Is more than
We know that sum of the measures of the supplementary angles is 180o
o
larger
exceeds
smaller
18 degrees
supplementary
You can solve the equations by any of the 4 methods
Substitution Method is preferable
As we can directly substitute (i) in (ii)