Professor Malone is grading papers in the teachers' lounge. She has already finished grading 20 assignments, and is grading 5 more assignments per hour. Her teaching assistant just came in to help her. He can grade at a rate of 7 assignments every hour. At some point, they will be finished and will have graded the same number of papers. How many assignments will they each have graded? Write a system of equations, graph them, and type the solution.