During four years of college, Nolan MacGregor's student loans are $4,000, $3,500, $4,400, and $5,000 for freshman year through senior year, respectively. Each loan amount gathers the interest of 2%, compounded quarterly, while Nolan is in school and 3%, compounded quarterly, during a 6-month grace period after graduation.

(c) If Nolan decides to pay an additional $60 per payment, how many payments will amortize the debt? (Round your answer to two decimal places.) ____ payments