Yvonne continues to work full-time at her job while she attends college part-time. It takes 5 years for Yvonne to complete the program, but when she does she is able to increase her salary from $37,000 per year to $45,000 per year. At this rate, Yvonne will have recovered her college costs after 4.5 years. How much did it cost Yvonne to go to college?