ПРЯМОКУТНИК.�КВАДРАТ

(65 + 19) + 5 =

(65 + 5) + 19 =

70

89

81 + (9 + 27) =

(81 + 9) + 27 =

90

117

(76 + 48) – 28 =

76 + (48 – 28) =

20

96

59 – (29 + 8) =

(59 – 29) – 8 =

30

22

10

12

14

1

3

4

6

8

10

х =

506 – 17

х =

489

506 – 489 = 17

х =

318 + 245

х =

563

563 – 245 = 318

17 = 17

318 = 318

b – a

а + b

a + (a + c)

(a + b) – c

m – a – b

b + c + d