4. The drama club is printing t-shirts for its members. The printing company chargesa certain amount for each shirt plus a setup fee of $40. There are 21 students in the drama club.
a. If there are 21 students in the club and the t-shirt order costs a total of $187, how much does each t-shirt cost? Show your reasoning.

Answer:   $7Step-by-step explanation:You want the cost of a shirt when the cost of 21 shirts plus a $40 setup fee is $187.CostThe total cost of the order is the sum of the setup fee and the extended cost of the shirts.   cost = (setup fee) + (number of shirts) × (cost per shirt)   187 = 40 + 21 × (cost per shirt)Subtracting 40 gives ...   147 = 21(cost per shirt)Dividing by 21, we have ...   7 = cost per shirtEach T-shirt costs $7.