The answer is 20 and let me tell you why. PEMDAS is the reason for this, you must multiply and divide first before you add and subtract, people that don't do this usually get the answer 320, which is incorrect, you must follow what called the "Order of Operations". Some will excuse it because there are no brackets, but I tell you that's wrong, because of the order of operations. (4x4)+(4x4)+4-(4x4) is the same as 4x4+4x4+4-4x4. Now if you did 4x2-1+5 your answer would be different if the problem was 4(2-1)+5, for the first one is 10 and the second one is 9.