Why is the answer 4? The reason why the answer is 4 is because 3/15 - 3/15 = 0 or 0/15. And since there was no fraction(s) or whole number(s) to regroup, 8 - 4 = 4. And DON'T say the answer is "40" 'cause it's not 40 at all, you just subtracted the <em>fraction </em>not the whole number.