Question 318781
I am going to show you how to do this by the substitution method because it is setup easier that way.

Step 1:
-7x+y=17
+7x     +7x
y=17+7x

Step 2:
-8x+7(17+7x)=-4
-8x+119+49x=-4
 119+41x=-4
-119     -119
41x=-123
41x/41 = -123/41
x=-3

Step 3:
y=17+7(-3)
y=17-21
y=-4

The final answer is x=-3 and y=-4