PE 6-3A Purchase transactions

MR Tile Company purchased merchandise on account from a supplier for $9,000, terms
2/10, n/30. MR Tile Company returned $1,500 of the merchandise and received full credit.
a. If MR Tile Company pays the invoice within the discount period, what is the amount of cash required for the payment?
b. Under a perpetual inventory system, what account is credited by MR Tile Company to record the return?

Answer:
a. $7,350. Purchase of $9,000 less the return of $1,500 less the discount of $150 [($9,000 – $1,500) × 2%)].
b. Merchandise Inventory