A paper company needs to ship paper to a large printing business. The paper will be shipped in small boxes and large boxes. Each small box of paper weighs 30 pounds and each large box of paper weighs 75 pounds. A total of 18 boxes of paper were shipped weighing 900 pounds altogether. Graphically solve a system of equations in order to determine the number of small boxes shipped, x, and the number of large boxes shipped, y.