Need help on this problem

If there are 12 moths and some have 31 days and others have 30 days how many have 28 days?

If you could answer these your a life saver

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.