A business operated at 100% of capacity during its first month, with the following results:

Sales (104 units)		$520,000
Production costs (130 units):
Direct materials	$65,000
Direct labor	16,250
Variable factory overhead	29,250
Fixed factory overhead	26,000	136,500
Operating expenses:
Variable operating expenses	$5,860
Fixed operating expenses	3,560	9,420

What is the amount of the contribution margin that would be reported on the variable costing income statement?

a.$422,180

b.$510,580

c.$425,740

d.$519,870