Problema Solution
Felipe purchased a prepaid phone card for $35.50. Calls cost 7 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)-35.50-0.07x . How much credit is left on the card after Felipe uses it for 40 minutes of calls?
Answer provided by our tutors
C(x)=35.50-0.07x
After 40 min call we have x = 40 min:
C(40) = 35.50 - 0.07*40
C(40) = $32.70
After 40 minutes call there are $32.70 left of the card.