which mult.-choice option represents cost of n sofas?

[Sarah2391]

During a sale on home furnishing, a customer can buy one sofa for 'x' dollars. Each additional sofa the customer buys costs 'z' dollars less than the first sofa. For example, the cost of the second sofa is x - z dollars. Which of the following represents the customer's total cost in dollars, for 'n' sofas bought during this sale?

a) x + (n - 1)(x - z)

b) x + n (x - z)

c) n (x -z)

d) x + (x - z) over n

e) (x - z) + (x - z) over n

HELP!!!

 

[soroban]

Re: HELP!!

Hello, Sarah!

During a sale on home furnishing, a customer can buy one sofa for \(\displaystyle x\) dollars.
Each additional sofa the customer buys costs \(\displaystyle z\) dollars less than the first sofa.
For example: the cost of the second sofa is \(\displaystyle x - z\) dollars.
Which of the following represents the customer's total cost for \(\displaystyle n\) sofas bought during this sale?

\(\displaystyle a)\;x + (n - 1)(x - z) \quad\;\; b)\;x + n (x - z) \quad\;\; c)\;n (x -z) \quad\;\; d)\;x + (x - z)/n \quad\;\; e)\;(x - z) + (x - z)/n\)

The first sofa costs \(\displaystyle x\) dollars.

Each of the other \(\displaystyle n-1\) sofas cost \(\displaystyle x - z\) dollars each.
They will cost: .\(\displaystyle (n-1)(x-z)\) dollars.

The total cost is: .\(\displaystyle x + (n-1)(x-z)\) . . . answer (a)