Answer:
May 10, purchased goods on account, terms 2/10, n/60
Dr Merchandise inventory 15,876
  Cr Accounts payable 15,876
May 11, purchased goods on account, terms 1/15, n/30
Dr Merchandise inventory 12,276
  Cr Accounts payable 12,276
May 19, paid May 10th invoice
Dr Accounts payable 15,876
  Cr Cash 15,876
May 24, purchased goods on account, terms 2/10, n/30
Dr Merchandise inventory 10,290
  Cr Accounts payable 10,290
Adjusting entry May 31 (purchase discounts lost on May 11th purchase)
Dr Purchase discounts lost 124
  Cr Accounts payable 124
Since the company didn't pay the invoice in time, accounts receivable increases by $124 to $12,400 total. The lost discount is considered an expense.