It would seem that the question is asking you to solve the equations algebraically, rather than by using the graph to find where the equations meet.
To solve algebraically, you just need to use the forms that you already have: y=mx+b.
The simple way is to take the RHS of both equations equal each other to find x. Then sub this x value into one of the original equations to find y. The results should be similar to those that you found on the graph.