Given x = 67 and y = 18, use two's complement to calculate:(1)x+y (2) x-y (3)-x+y (4)-x-y. Do the calculation, show the results in 8­-bit two's complement binary form first, then convert the results into decimal (For negative decimal numbers enter a minus sign. For positive decimal numbers, however, do NOT enter a plus sign).

(a) x + y =
(b) x - y =