20 points and solve the system of linear equations. separate the x- and y- values with a coma. -9x+6y=-30 -12x+9y=-30

Alright, so we have
-9x+6y=-30
-12x+9y=-30

Although we might really want to say -9x+6y=-12x+9y, we can't do it that way. We have to get rid of a variable and go from there. Solving for y, we get
-9x+6y=-30
Divide both sides by 3
-3x+2y=-10
Add 3x to both sides
2y=-10+3x
Divide both sides by 2
y=(-10+3x)/2

-12x+9y=-30
Divide both sides by 3
-4x+3y=-10
Add 4x to both sides
-10+4x=3y
Divide both sides by 3
(-10+4x)/3=y

Since we have 
(-10+4x)/3=y and y=(-10+3x)/2 , we have
(-10+4x)/3=(-10+3x)/2
Since 3*2=6, we can multiply both sides by 6
-20+8x=-30+9x
Add 30 to both sides
10+8x=9x
Subtract 8x from both sides
x=10
Plug that in to any equation,and you should have your answer! Good luck, and ask if you have any questions!