Omar Corporation paid one of its sales representatives $4,300 during the month of March. The rep is paid a base salary plus $15 per unit of product sold. During March, the rep sold 200 units. Calculate the total monthly cost of the sales representative’s salary for each of the following months: April 240 units sold, May 150 units sold, June 250 units sold, and July 160 units sold. Find the following total variable cost, total fixed cost, and total salary cost for each month.