Suppose you purchase a house for $559,047 using a 30-year fixed-rate mortgage. You agree to make a down payment of $37,897 today. In addition, you agree to pay $89,990 in 6 years and $29,971 in 8. Find the size of your monthly payment you should ask for from your bank if interest rates are currently 6.03% and payments are made at the end of the month with the fist payment due at the end of this month.

The answer that is given is 2,645.91 but I'm not sure how to get there. Can someone help me?