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

man be x and son be y
x/y=3
x-5/(y-5)=4
x-5=4y-20
since x=3y
3y-5=4y-20
y=15
so man =15yrs and father =45yrs

Answer 2

Hi !

Let the preset ages of the man and his son be "x " and "y" respectively.

as per the question,
x = 3y                                 -------> (1) 

ages five years ago,
age of father = 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 :-
age of father = x = 45 years
age of son = y = 15 years