need help determining invoice amount

Purchase-Related Transactions The debits and credits from four related transactions, (1) through (4), are presented in the following T accounts. Assume that the freig terms were FOB shipping point and that the credit terms were 1/10, n/30. Cash Accounts Payable (2) 150 (3) 1,980 (1) 13,860 11,880 (4) 11,880 Inventory (1) 13,860 (3) 1,980 (2) 150 a. Describe each transaction. 1. Purchased merchandise on account net of discount. 2. Paid freight 3. An allowance for return of merchandise was granted by the creditor. 4. Paid the balance due within the discount period. b. Determine the invoice amount of the merchandise that was returned in (3) 1,999.8 X