richard klein works as auto mechanic and earns the following commission rates 3.00 percent for oil changes 5.00 percent for tune ups and 6.25 percent on auto parts sales he is guaranteed a minimum salary of $2,450.00 per month last month he brought in $2,500.00 in oil changes $4,500.00 in tune ups and sold $28,200.00 in parts what is his gross pay for the month