Barbara buys a box of pens for $4. for every additional box she buys, she gets a $1 discount. which expression represents the total cost of the pens, c, as a function of the number of boxes, b?

Step-by-step explanation:

We have been given that Barbara buys a box of pens for $4.  

We are also told that for every additional box she buys, she gets a $1 discount. After discount price would be $3 per box.

Since the discount is not applied for 1st box, so the number of boxes with discount would be .

The cost of boxes after discount would be .

The total cost of boxes would be cost of 1st box plus cost of boxes after discount: .

Since the total cost of the pens, c, as a function of the number of boxes, b, so our required function would be .