Question

In 12 years a man will be three times as old as his son;the difference of their present ages is 30 years.find their present ages

Answer 1

let present age of
son=x
then,father=x+30

after 12 years age of
son=x+12
father=x+30+12=x+42

from question
3(x+12)=x+42
or,3x+36=x+42
or,3x-x=42-36
or,2x=6
or,x=3

so present age of
son=x=3 years
fathet=x+30=3+30=33

hope this help you