use the following information to answer this question callaham corporation is contin 460480

Use the following information to answer this question.

Callaham Corporation is a wholesaler that sells a single product. Management has provided the following cost data for two levels of monthly sales volume. The company sells the product for $115.80 per unit.

Sales volume (units)

4,000 5,000

Cost of sales $338,000 $422,500

Selling and administrative costs $89,600 $106,000

The best estimate of the total monthly fixed cost is

A. $24,000.

B. $427,600.

C. $478,050.

D. $528,500.

I’d really like to know how to get the answer more than anything. I’m not really sure where to start on this, I saw where someone had added the cost of sales and selling & administrative costs together, but then that gives me 2 answers and I can only choose one. Please show me how to get this. Thanks in advance!