Question

a man is thrice as old as his son.five year ago the man was four times as old as his son..find their present ages

Answer 1

let the age of the son be x 
then the age of man be 3x 
before five years the age of son be y and  the 
age of man be 4y  that i understood from this question 

Answer 2

hello!

present age of son=x years
present age of man=3x years

5 years ago man's age=(3x-5) years
5 years ago son's age=(x-5) years

BTP,

3x-5=4(x-5)
=>3x-5=4x-20
=>-x= -15
=>x=15

Son's present age is 15 years.
Man's present age is 45 years.

hope it helps... :)