please do by hand thank you

Joanne repays a loan amount 200,000 with 72 end of month payments. The nominal interest rate is 15% convertible monthly. For the first 12 payments the payments are three times the interest. The remaining payments have equal principal. Just after Joanne makes her 12th payment the lender sells the rights of future payments. The new lender pays for the payments is based on a nominal rate of 18% convertible monthly. find the annial effective yield rate for the lender