SOLUTION: I need help with step by step elimination method solving for x,y. y=-4 -3x-6y=15

Algebra ->  Coordinate Systems and Linear Equations -> SOLUTION: I need help with step by step elimination method solving for x,y. y=-4 -3x-6y=15      Log On


   

Question 863483: I need help with step by step elimination method solving for x,y.
y=-4
-3x-6y=15
Answer by ben720(159) About Me  (Show Source):
You can put this solution on YOUR website!
Because y=-4, you can substitute -4 for y in the second equation:
-3x-6%28-4%29=15+=-3x-6y
Multiply
-3x%2B24=15
Subtract 24 from both sides
-3x=-9
Divide both sides by -3
x=3

x=3