Gibson Entertainment sells souvenir T-shirts at each rock concert that it sponsors. The shirts cost $7 each. Any excess shirts can be returned to the manufacturer for a full refund of the purchase price. The sales price is $22 per shirt. Required a. What are the total cost of shirts and cost per shirt if sales amount to 2,000,2,500,3,000,3,500, or 4,000 ? b. Is the cost of T-shirts a fixed or a variable cost? Complete this question by entering your answers in the tabs below. a. What are the total cost of shirts and cost per shirt if sales amount to 2,000,2,500,3,000,3,500, or 4,000 ? b. Is the cost of T-shirts a fixed or a variable cost? Complete this question by entering your answers in the tabs below. Is the cost of T-shirts a fixed or a variable cost