Question

Answer 1

A

53 .39 + 47 . 39 - 53 . 21 - 47 .21

= (53 + 47) . 39 - (53 + 47) . 21

= 100 . 39 - 100 . 21

= 100 . (39 - 21)

= 100 . 18

= 1800

B

2 x 53 x 12 + 4 x 6 x 87 - 3 x 8 x 40

= 24 x 53 + 24 x 87 - 24 x  40

= 24 x ( 53 + 87 - 40 )

= 24 x 100

= 2400

C

 5 x 7 x 77 - 7 x 60 + 49 x 25 - 15 x 42 

= 7 x 77 x 5 - 7 x 60 + 7 x 7 x 25 - 15 x 6 x 7

= 7 x 385 - 7 x 60 + 7 x 35 - 7 x 90

= 7 x ( 385 - 60 + 35 - 90 )

= 7 x 270

= 1890

 

 

Answer 2

a) 53.39 + 47.39 - 53.21 - 47.21

= 53.(39-21) + 47.(39 -21)

= 53. 18 + 47. 18

= 18.(53+47)

= 18. 100

= 1800

b) 2.53.12 + 4.6.87 - 3.8.40

= (2.12).53 + (4.6).87 - (3.8).40

= 24.53 + 24.87 - 24.40

= 24.(53 + 87 - 40)

= 24.100

= 2400

c) 5.7.77 - 7.60 + 49.25 - 15.42

= 5.7.77 - 7.60 + 7.7.25 - 15.6.7

= 385.7- 7.60 + 7.175 - 90.7

= (385-60+175-90).7

= 410 .7

= 2870