The following information is available for the past month for a retail store:

Sales $87,000

Markups $9,000

Markdowns $9,000

Purchases (at cost) $38,800

Purchases (at retail) $107,000

Beginning inventory (at cost) $30,000

Beginning inventory (at retail) $48,186

What is the ending inventory at cost using the conventional retail method?

$38,870

$164,186

$78,000

$28,570