3X - 4Y = 9
-3X + 2Y = 9
first step is try to get rid of one of the variables and solve for the other one. In this example you dont need to manipulate the equations to get one variable to cancel.
the x term cancels out. add both equations
-2y = 18
y= - 9
now we plug the y term back into an original equation and solve for x
3x - 4(-9)=9
3x=-27
x=-9
hope that helps