The ratio of ages of Krishna and Balram is 3:4. Four years earlier the ratio was 5:7. Find the present ages of Krshna and Balram:

Explanation

Let the present age of Krishna and Balram be 3x and 4x Four years ago their ages be (3x-4) and (4x-4) S0, `(3x-4)/(4x-4)=5/7 implies 7(3x-4)=5(4x-4)`
`implies 21x-28=20x-20`
`implies ` x=8
therefore present age of Krishna =3x=24 years and age of Balram=4x=32 years