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The Problem

The ages of a & b are in the ratio 7:5. After 10 years the ratio of their ages will be 9:7.The present age of B = ?

Answer provided by our tutors

let x = the multiplier

then

7x = A's present age

and

5x = B's present age

:

Adding 10 yrs to their age produces a ratio of 9:7, there

 = 

cross multiply

7(7x+10) = 9(5x+10)

49x + 70 = 45x + 90

49x - 45x = 90 - 70

4x = 20

x = 20/4

x = 5 is the multiplier

:

Their present ages

A: 5(7) = 35 yrs

B: 5(5) = 25 yrs

 

 

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