William is a 45 year-old civil engineer with a good work-life balance, but he is considering pursuing his MBA. It would take him three years of night courses to graduate, and he estimates that tuition would cost about $25,000 a year. After he receives his MBA, he would apply be a team leader, but William does not have any further desire to advance into management. The difference in salary between civil engineer and team lead is $8,000 annually. To pay for the MBA, William is going to borrow money from his 401k. William has been getting an average return of 8% in his 401k. William wants to retire at age 65.

William current employer doesn't reimburse tuition for graduate school, but he could work for another firm. If William finds a firm that will pay for his tuition but the salary is lower, how much of a salary reduction could he afford to take?