Answer:
Step-by-step explanation:
y = 6
x = 9
x+7y
9 + 7(6)
9+ 42
51
The first one is -2x^2 - 21x + 4, the second one is -15 (I think, not 100% sure), the third one is 4xyz + 3yz + 5x - 4 (also not 100% on this one)