Okay!
This problem is a systems of equations - graphically, your answer will be where all the lines in the problem/system intersect.
You are given two rates at the beginning of the problem:
Keith's rate: 6 pages a day
Tameka's rate: 5 pages a day, 15 page headstart.
When you are given a rate, that is automatically a line! That's what makes these systems of equations really neat.
Try taking Keith and Tameka's rates individually and come up with an equation for the both of them, and then put the two on a graph.
(hint: substitute <em>x</em> for pages)
Good luck!