Answer:
Sept 6. DR Inventory (80 * 20) 1,600
CR Accounts Payable $1,600
Sept 9. DR Inventory 80
CR Cash 80
Sept 10. DR Accounts Payable 63
CR Inventory 63
Sept 12. DR Accounts Receivable (26 * 31) 806
CR Sales Revenue 806
DR Cost of Goods Sold (21 * 26) 546
CR Inventory 546
Sept 14. DR Sales Returns and Allowances 31
CR Accounts Receivable 31
DR Inventory 21
CR Cost of Goods Sold 21
Sept. 20 DR Accounts Receivable (30 * 32) 960
CR Sales Revenue 960
DR Cost of Goods Sold (30 * 21) 630
CR Inventory 630