Salvadore Inc., a local retailer, has provided the following data for the month of September:

Merchandise inventory, beginning balance $ 49,500Merchandise inventory, ending balance $ 42,900 Sales $268,500 Purchases of merchandise inventory $138,700 Selling expense $ 18,800 Administrative expense $ 53,800

The net operating income for September was:

a) $50,600

b) $130,800

c) $129,800

d) $48,300