The answer is 4. According to the commutative property, you can commutate (swap) numbers over and get the same result. However, it only works for addition and multiplication. For instance, x + y = y + x. Or, x y = y x. In our example, we have 7 4 = ? 7. Because we already have 7 on the right side of the expression, the missing number will be 4.
