Question

A man is thrice as old as his son 5 years ago the man was 4 times as old as his son find their present ages

Answer 1

Hey there!

Let the present age of the Man = x yrs.
& Present age of son = y yrs.

ATQ,
x = 3y -----(1)

Five years ago:

Age of man = x - 5
Age of son = y - 5

So,
x - 5 = 4(y - 5)
x - 5 = 4y - 20

from equation (1) 

3y - 5 = 4y - 20

4y - 3y = -5 + 20

y = 15

x = 3y

x = 3 × 15
   = 45

Hence, present ages of father and son are :-

Present age of Man = x = 45 years
& Present age of Son = y = 15 years

Cheers!

Answer 2

let the son's present age be x
man =3x
5 years ago,
son's age=x-5
man=4(x-5)=4x-20
ATQ
3x+x=x-5+5+4x-20+5
4x=5x-15
5x-4x=15
x=15

son's present age=15
man's present age=3×15=45

hope this answer will help you.