Question

The ages of Hari and Harry are in the ratio $5:7$. Four years from now the ratio of their ages will be $3:4$. Find the sum of their present ages.

Answer 1

The ratio of Hari's and Harry's present ages is 5:7

So, let their ages be $5x$ and $7x$

After 4 years their ages will be in ratio 3:4

Therefore,$(5x+4)/(7x+4)=3/4$

or, $4(5x+4)=3(7x+4)$

or, $20x+16=21x+12$

or, $16-12=21x-20x$

or, $4=1x$

or, $x=4$

Therefore, present age of Hari = $5x=(5\times 4)=20$ years.

Present age of Harry $=7x=(7\times 4)=28$ years

The sum of their age is $28+20=48years$