Answer:
x = -4 and y = 12
Step-by-step explanation:
Since you have y = -x + 8 you can substitute this into the first equation where y was so you have 3x + 4(-x + 8) = 36.
That way, there is only one variable and it is easier to solve.
3x + 4(-x + 8) = 36
3x -4x + 32 = 36
-x +32 = 36
-x = 4
x = -4
Plugging this into the equation y = -x +8,
y = -(-4) + 8
y = 4 + 8
y = 12
