Answer:
1. Purchased $11,000 of supplies on account.
Dr Supplies 11,000
  Cr Accounts payable 11,000
2. Earned and collected $28,000 of cash revenue.
Dr Cash 28,000
  Cr Sales revenue 28,000
3. Paid $9,500 cash on accounts payable.
Dr Accounts payable 9,500
  Cr Cash 9,500
4. Adjusted the records to reflect the use of supplies. A physical count indicated that $2,600 of supplies was still on hand on December 31, Year 2.
Dr Supplies expense 8,400
  Cr Supplies 8,400