Question

Two numbers are in the ratio 7:9 When each of these numbers is decreased by 4 then their ratio becomes 5:7 Find the sum of two numbers
​ a) 30
b) 24
c) 32
d)20

Answer 1

Answer:

The answer is (b) 24

Step-by-step explanation:

we have 9:7

so let it be 9x / 7x

if we subtract 4 from each then ,=

7x-4 / 9x -4

the ratio becomes 5:7 =

5x/7x = 5/7

so , 7x-4/9x-4 = 5/7

By cross multiplication,

7(7x- 4 ) = 5(9x-4)

49x-28 = 45x-20

49x - 45x = -20 +28

4 x = 8

x = 8/4

x= 2

so we have 7x -4 and 9x - 4

x = 2

7×2-4 + 9×2-4

= 14-4 + 18-4

= 10 + 14 = 24

Thanks