Elkins Corporation uses the perpetual inventory method. On March 1, it purchased $30,000 of inventory, terms 2/10, n/30. On March 3, Elkins returned goods that cost $3,000. On March 9, Elkins paid the supplier. On March 9, Elkins should credit

Explain why I must credit inventory for $540. I understand $30,000-3000= $27,000 and since Elkins paid within the 10 days period the company gets 2% off which is $27,000 x 2%= $540

I though that the JOURNAL ENTRY WAS:

A/P $27,000 (debit)

PURCHASE DISCOUNT $540 (credit)

CASH $26,460 (credit)

Answer is Credit inventory $540 please explain why and show journal entry.