This is a system of equations. The best way to solve it is by realizing that you have two equations equal to y. Since y = y, it follows that 
. Solving for x, you get 4.
Then, substitute 4 into one of the original equations to find y.
.
The solution is
. I have attached a graphical representation of the solution as well.
Then, substitute 4 into one of the original equations to find y.
The solution is