Thirty-six friends are renting a party bus to the school prom. Rental of the party bus will cost $300 up front plus $18 per hour
. The friends have the bus from 5:00 PM to 3:00 AM. Each friend has agreed to chip in $12. One of the teachers at the high school, Mr. Jones, has offered to chip in the rest. If he does, how much will he pay?