problem: 1st firm sold merchandise on credit to 2nd firm for $1,000 on July 1, with terms of 2/10, net/30. On July 6, 2nd returned $200 worth of merchandise stating the materials was defective. On July 8, 1st received a payment from 2nd & credited Accounts receivable for $450. On July 24, 2nd firm paid remaining balance on their account. find out the total cash received from second during July?