Question

Before 7 years the ratio of ages of a and b was 3:4.After 9 years ratio of their ages will be 7:8.What os the present age of b

Answer 1

Answer:

9 years is the correct answer.

Step-by-step explanation:

Ratio of ages of A and B = 5:3

Let the common multiple for age be 'x'.

The ages 7 years ago are 3x and 4x .

9 years later A's age is 3x+9  

After 6 years B's age is 4x+9

$\frac{\left(3x+9\right)}{\left(4x+9\right)\:}\:=\:\frac{7}{8}\:\left(Given\right)\\\left(3x+9\right)\cdot \:8=\left(4x+9\right)\cdot \:7\\24x+72=28x+63\\-4x=-9\\x=\frac{9}{4}$

Required age of B $= 4\times \frac{9}{4}\:=\:9\:years$

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