Question

deandre purchased a prepaid phone card for $15.50. calls cost 15 cents a minute using this card. the credit, c (in dollars), left on the card after it is used for x minutes of calls is given by the following function.
c(x) = 15.50 - 0.15x
how much credit is left on the card after deandre uses it for 40 minutes of calls?
dollars

Explanation:

Step1: Identify the function and input

The function is \( C(x) = 15.50 - 0.15x \), and we need to find \( C(40) \) (since \( x = 40 \) minutes).

Step2: Substitute \( x = 40 \) into the function

Substitute \( x = 40 \) into \( C(x) \):
\( C(40) = 15.50 - 0.15(40) \)
First, calculate \( 0.15(40) = 6 \).
Then, \( C(40) = 15.50 - 6 = 9.50 \).

Answer:

9.50