Question

Lucy purchased a prepaid phone card for $15.25. Calls cost 9 cents a minute using this card. The credit, C (in dollars), left on the card after it is used for xminutes of calls is given by the following.C=15.25-0.09xHow much credit is left on the card after Lucy uses it for 50 minutes of calls?

Answer 1

Use the given model to arrive at your answer:

C(x) = 15.25 - 0.09x, where C= credit, in dollars; x=time, in minutes.

When x=50 minutes,

C(x)= 15.25 - 0.09(50)

C(x)= 15.25 - 4.5

C(x)= $10.75

In summary, $10.75 will be left after 50 minutes of usage.