Page 36 - ICSE Math 7

 3  5 3    3 15 
= 8 of  +  ×   = 8 of  + 
 5  16 2   5 32 

 3×32 15×5+   96 75+ 
= 8 of   = 8×  
 160   160 

8 ×171 171 11
= = = 8
160 20 20 20

Example 16: Simplify the following.

3   7  3 1 1     1 1 1  1 1
(a) of  +  ÷ −   (b) 5 − 2 + of 5 ÷ 2
19  9  4 2 3       4 3  3   2 5  

1
(c) 5 of   21  +  1 ÷ 4   1 + 3     × 3 
3  24 7  5 7   8 

3   7  3 1 1    3  7  3 3 −  2 
Solution: (a) of  +  ÷ −   = of  +  ÷  
19  9  4 2 3     19  9  4 6  

3  7  3 1   3   7 3 6  3 
⇒ of  +  ÷   = of  + × 
19 9   4 6   19   9 4 2 1  

3  7 9  3  7 × 2 +×  9 9 3  14 + 81
⇒ of  +  = of   ⇒ of  
19  9 2  19  9 × 2  19  18 

3 95 3 1 95 5 5
⇒ of = × =
19 18 19 1 18 6 6


(b)   5 1 − 2 1  + 1 of 5 1 ÷ 2 1   =   21 − 7   + 1 of   11 ÷ 11 

 4 3 3  2 5   4 3  3  2 5 
63 – 28 1 11 5 35 1 5
= + of × = + ×
12 3 2 11 12 3 2

35 5 35 + 5 × 2 35 + 10 45 15 15 3
⇒ + = ⇒ = = = 3
12 6 12 12 12 4 4 4

1  21  4  1 3   3 16  21  11  1×7 3×5  +  3
(c) 5 of  +  1 ÷  +   ×  = of  +  ÷    × 
3  24 7  5 7   8  3  24  7  35   8 

16  21  11  7 15  +  3 16  21   11 35  5  3 
= of  +  ÷    ×  = of  +  ×  × 
3  24  7  35   8  3   24   7 22 2   8 

16  21 5 3 16  21 15 16  21×2 15×3+ 
= of + × = of  +  = of
3   24 2 8  3  24 16  3   48  

16  42 45+  16 87 16 87 29
= of = of = ×
3   48   3 48 3 48 3
29 2
= = 9
3 3

22