Solving systems by elimination, subtraction
3x-2y= -1
3x-4y= 9

Multiply 3x-4y=9 by -1 to get -3x+4y=-9
Add 3x-2y=-1 and -3x+4y=-9 to get 2y=-10
Divide both sides by 2 and you get y=-5
Now, substitute y back into any equation, I'm going to choose 3x-2y=-1, and you get 3x-10=-1.
Add 10 to both sides and you get 3x=9, divide both sides by 3 to get x=3.
Hopefully this helps~