Eight years ago Mr Fontana was six times as old as his son I

Eight years ago, Mr. Fontana was six times as old as his son. In twelve years time, he will be twice as old as his son. How old are they now?

Solution

Equation 1:

f - 8 = 6*(s - 8)

6s - f = 40

equation 2:

f + 12 = 2*(s + 12)

2s - f = -12

Solving both equation:

6s - f = 40

2s - f = -12

Subtract both equation:

4s = 52

s = 13 yrs

2s - f = -12

f = 26 + 12

f = 38 yrs