Melinda is planning to attend a private university after she graduates from high school in 3 years. She is devising a plan to save money each month to help with the expenses of attending the university. The cost of attending the private university for one year is $22,500. Her family has promised to contribute $13,500 each year she is in school. Which plan shows the minimum amount of money Melinda must contribute to her savings to have enough money to pay for her first year of tuition?