Question 387509
First, we'll plug the value of y into the first equation. 
8x-2y=-100
8x-2(3x+36)=-100
8x-6x-72=-100
Then, we'll combine both x's
2x-72=-100
Next, we subtract 72 from both sides of the equation.
2x=-28
x=-14
Then, we can find the value of y, by substituting x into the second equation.
3x+36=y
3(-14)+36=y
Then, we just do the math.
-42+36=y
-6=y
Finally, we can check the answer.
8x-2y=-100
I'll plug in the values for x and y.
{{{(8*-14)-(2*-6)}}}=-100
-112-(-12)=-100
-112+12=-100
-100=-100
Since negative 100 is equal to negative 100, the values of x and y are true.