During its first month of operations, Perfects Pets purchased 6,300 bags of dog food at a cost of $3 a bag and sold all 6,300 bags of dog food on account with payment terms of $ 1/10, net 30 for $10 each. A total of 2,000 of these bags were sold to customers who paid within the discount period; the other customers paid after the discount period had ended. Sales allowances totaling $200 were granted to customers whose dogs did not like the dog food. 

a. Calculate the gross profit for the month 

b. Calculate the gross profit percentage for the month.