Multiply the first equation by -2. It turns into 4x+18y=50 and the other one stays -4x-9y=-23. Then you "eliminate" the equations by "adding" them. Set it up like this: 4x+18y=50 + -4x-9y=-23 4x-4x= 0. 18y-9y= 9y and 50-23= 27 SO: 9y= 27 and y= 3 And then you plug that in to one equation: 4x +18(3)= 50. 4x= 50-(18*3) 4x= -4, so x=-1. Plug it back in to check! Hope this helps. Happy solving! :)
Tyw23456 explained it quite masterfully, but here is another way to solve the system. Start by multiplying one equation by -1 so later when we add them, the like terms with variable y will be eliminated so we can solve for x:
-1(-2x - 9y = -25) <span>→ (2x + 9y = 25)</span>
Now add the equations (we can factor a -1 out of the bottom equation for a subtraction problem):