Rolex borrowed 3600 from a credit union for 6 months at an interest rate 10% per year. how much did he owe the credit union at the end of the six months?

Dean and karlene get paid to write songs. dean is paid a one-time fee of $20 plus $80 per day. karlene is paid a one-time fee of $25 plus $100 per day. write an expression to represent how much a producer will pay to hire both to work the same number of days on a song.