Solomon Corporation paid one of its sales representatives $4,000 during the month of March. The rep is paid a base salary plus $10 per unit of product sold. During March, the rep sold 300 units. Required Calculate the total monthly cost of the sales representative's salary for each of the following months: April May June July 200 320 180 360 Month Number of units sold Total variable cost Total fixed cost Total salary cost $ 0 $ 0 $ 0 $ 0