Question

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?

Answer 1

Let b=the number of boxes, c=cost of the pens
The expression that represents the total cost of the pens if a box costs 4 dollars and then she gets a 1 dollar discount for every additional box is c(b)=3b+1. We got this from the original equation c(b)=4+(4-1)(b-1). Simplify this and you will get c(b)=3b+1.

Answer 2

`c(b)=4+3(b-1)`

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
`b-1`.

The cost of boxes after discount would be
`3(b-1)`.

The total cost of boxes would be cost of 1st box plus cost of boxes after discount:
`4+3(b-1)`.

Since the total cost of the pens, c, as a function of the number of boxes, b, so our required function would be
`c(b)=4+3(b-1)`.