The only way to solve this system of equations is by elimination (multiplication). Let's say that we want to cancel out the x. You multiply the first equation by 5 and you multiply the second equation by 2.
Your equations now are:
10x-5y=55 and 10x+6y=-22
You can subtract these equations to get -11y = 77.
Now that we know that y = -7, we can substitute y in to solve x.
