Rob quit a job working 20 hours per week at a subway sandwich shop to make sandwiches

Rob quit a job working 20 hours per week at a subway sandwich shop to make sandwiches himself in his college dorm room that he sells to hungry students. if he had been paid $9 per hour at subway and now works the same 20 hours per week but sells his sandwiches for $300 a week and pays only $100 a week for supplies how much economic profit does he make?