All to one side:
4x^2-32x+64 = 0,
divide by 4:
x^2 -8x + 16 = 0
apply formula or see that it is (x-4)^2!, so only x =4 is a root and it is double.
17X-7Y. You add or subtract the same variables, in this case you only have two x's and one y. So you add them, because you have a addition sign. 13x+4x and you leave the Y alone, because there is not another Y variable.
The answer is 11x11x11=1331