Solve the system by substitution.

Question

x + 3y = -4
2x + 2y = -8

Answer 1

x + 3 y = - 4 Multiply both sides by 2

2 x + 6 y = - 8

2 x + 6 y = - 8
-
2 x + 2 y = - 8
_____________________

- 4 y = 0

y = 0

x + 3 y = - 4

x + 3 * 0 = - 4

x + 0 = - 4

x = - 4

Te solutions are :

x = - 4 , y = 0

Answer 2

Nice job using elimination. For substitution, though, note that

x = -4-3y
so, substituting that into the other equation, we have

2x+2y = -8
2(-4-3y)+2y = -8
-8-6y+2y = -8
-4y = 0
y=0
so, x=-4-3y = -4

as found above