Answer:
Step-by-step explanation:
-3x + 4y = -20
y = x - 4
Put the second equation into the first equation in place of y.
-3x + 4 (x - 4) = -20
Multiply everything in the parenthesis by 4.
-3x + 4x - 16 = -20
Combine like terms.
x - 16 = -20
Add 16 to both sides.
x = -4
Put this into the second equation in place of x.
y = -4 - 4
y = -8
Your solution set is (-4,-8).
Hope this helps!