Bob decided to give up a full-time salary of $45000 a year to go to school for 4 years. The total cost of going to school will not include the loss of income because he has saved money and has grants/scholarships to support living cost during this time. But the cost of going to school will be $2,858 per semester, plus $391 per semester for books. If he wants to recover his investment in 6 years or less what is the minimum salary he would need to earn upon earning his degree.