Let x = Parent's age now y = son's age now
Then, x-5 = parent's age five years ago
y-5 = son's age five years ago
So, x-5 = 5(y-5)
Simplify to get x - 5y = -20
Parent's age 8 years from now = x+8
Son's age 8 years from now = y+8
So, x+8 = 3(y+8)
Simplifying, we have x - 3y = 16
We have the system of equations: x - 5y = -20
x - 3y = 16
Subtract the equations to obtain -2y = -36
y = 18
x = 70
Parent is 70 years old and the son is 18 years old.