Question

4 years ago, the ratio of the ages of A and B was 2:3 and after 4 years it becomes 5:7. Find their present ages​

Answer 1

Answer:

Let the present age of A and B be A and B respectively.

Given that A−4B−4=35 _ _ _ _ (i)(Before 4 years)

and A+4B+4=57 _ _ _ _ _ _ _ _ (ii)( After 4 years)

Cross multiplying equation (i) gives

5A−20=3B−12

i.e 5A−3B=8 _ _ _ _ _ _ _ _(iii)

And cross multiplying (ii) gives

7A+28=5B+20

i.e 7A−5B=−8 _ _ _ _ _ _ _ _ _ (iv)

Now substituting equation (iv) in (iii) we get

5A−3B=−(7A−5B)

i.e 5A−3B=5B−7A

i.e 12A=8B

Therefore A:B = 2:3

Their present ages are in the ratio 2:3