Question

Your father is thrice your age. Five years ago, he was 4 times your age. Fing both of your ages.

Answer 1

F = 3I
F-5 = 4(I-5)
3I-5 = 4I-20
-I = -15
I = 15
F = 45

Answer 2

Let the age of mine be x years 
and my father age be y years.

Then A.T.Q

1. 3x = y   ---------------------------------(1)

2. Five years ago
4(x - 5)  =   y - 5
4x - 20 = y - 5
4x - y = -5 + 20 = 15

Putting the value of y in the equation

4x - 3x = 15
x = 15

Putting the value of x in (1)

3(15) = y
y = 45
       
                  Hence the age of mine is 15 years 
                  And my father age is 45 years.