Chapter 4.7, Problem 22P

You have a gift card for a coffee shop worth $90. Each day you use the card to get a coffee for $4.10. Write an explicit formula to represent the amount of money left on the card as an arithmetic sequence. What is the value of the card after buying 8 coffees?

To determine

To find:The formula and the value of the card after buying 8 coffees.

Answer to Problem 22P

The formula is $V=\$90-\$4.10n$ and the value of the card after buying 8 coffees is $\$57.2$

Explanation of Solution

Given:

The gift card for coffee shop is $90

The card to get a coffee is $4.10

Calculation:

The required formula is,

  $V=\$90-\$4.10n$

Here, V is the value of the card and n is the number of coffee bought.

Substitute 8 for n in the above equation.

  $\begin{array}{c}V=\$90-\$4.10\left(8\right)\\ =\$90-\$32.8\\ =\$57.2\end{array}$

Thus, theformula is $V=\$90-\$4.10n$ and the value of the card after buying 8 coffees is $\$57.2$