18. A department receives a 10 percent discount on its purchases of computer paper. In February 500 reams of computer paper were purchased at $1.21 per ream and in March 250 reams of computer paper were purchased at $1.25 per ream. What was the total discount for the two months? OA. $183.50 OB. $312.50 OC. $605.00 OD. $917.50 OE. None of the above