The combined age of a father and his two sons is 50 years. Four years ago the father was eight times as old as his older son. Four years from now he will be 4 times as old as his younger son. Find the age of each at present.

Question

I found that the ages are 36, 8, 6
But I want to learn how to find it out by using mathematical expressions.

Answer 1

If the sons are age a and b, with a<b,
f+a+b = 50
f-4 = 8(b-4)
f+4 = 4(a+4)

Answer 2

16