Delta Ltd. sold merchandise (Delta's cost, $1,000), to Gamma Ltd. for $3,000, terms 2/10, n/30. Five days later Gamma returned $300 of the merchandise to Delta (Delta's cost $100). Required: Prepare the journal entries required to record the following transactions: a) The sale on Delta's books assuming Delta uses the perpetual inventory system. b) The purchase on Gamma's books, assuming Gamma uses the perpetual inventory system. c) The return on Delta's books, assuming Delta uses the periodic inventory system. d) The payment, with-in the discount period, on Gamma's books, assuming Gamma uses the perpetual inventory system