I know the answer to the problem but can someone please give detail steps, please?

Miller, Inc. estimates the cost of its physical inventory at March 31 for use in an interim financial statement. The rate of markup on sales is 20%. The following account balances are available:

Inventory, March 1 $220,000

Purchases 172,000

Purchase returns 8,000

Sales during March 350,000

The estimate of the cost of inventory at March 31 would be

a. $34,000.

b. $104,000.

c. $121,500.

4. $78,000.