Answer:
The journal entries to record the whole purchase and payment process are:
May 1, purchase of merchandise on account
Dr Merchandise inventory 400
Cr Accounts payable 400
May 3, defective merchandise returned
Dr Accounts payable 50
Cr Purchase returns and allowances 50
Dr Purchase returns and allowances 50
Cr Merchandise inventory 50
May 10? payment of merchandise account
Dr Accounts payable 350
Cr Cash 343
Cr Purchases discounts 7
