a) x = -8
x coordinate has been given, we need to find y coordinate of the ordered pair.
By substituting x = -8 in the equation we can find y
8y + 7x = -56
8y + 7 * -8 = -56
8y -56 = -56
8y = 0
therefore y = 0
(-8,0)
b) y = 7
we need to substitute y = 7 into the equation to find x
8*7 + 7x = -56
56 + 7x = -56
7x = -56 - 56
x = -112/7
x = -16
(-16,7)