You can
put this solution on YOUR website! .
Answer. Kobby is 12 years old; Kofi is 48 years old.
Actually, this problem can be solved mentally and momentarily, as soon as you completed reading the condition.
But if you want to use Algebra, here it is:
4x - x = 36
3x = 36
x = 36/3 = 12 is the Kobby age.