Douglas Company is a merchandising company. During the next month, the company expects to sell 400 units. The company has the following revenue and cost structure: Selling price per unit $240 Cost per unit $135 Sales commission 12% of sales Advertising expense $16,000/month Administrative expense $33,500/month What is the expected contribution margin next month?

The answer is $30,480 but can you show me how I get there?