Question

Recon Cellular Company charges its cell phone customers $19.95 a month for the first 60 minutes of air time plus $0.39 for each additional minute beyond 60 minutes. a) Find the cost to talk for 155 minutes in one month.b) How long can you talk for $35 in one month?

Answer 1

Data:

For first 60 minutes: $19.95

plus per extra minute: $0.39

Time (in minutes): t

You have the next equation for the given situation:

C: cost

t: time

`C=19.95+0.39(t-60)`

a) find the cost (C) to t=155minutes

Substitute in the equation the t for 155 and calculate the C:

`\begin{gathered} C=19.95+0.39(155-60) \\ C=19.95+0.39(95) \\ C=19.95+37.05 \\ C=57 \end{gathered}`

For 155 minutes the cost is $57 in one month

b) find the t for C=$35

Substitute in the equation the C for 35 and solve for t:

`\begin{gathered} 35=19.95+0.39(t-60) \\ 35=19.95+0.39t-23.4 \\ 35=-3.45+0.39t \\ 35+3.45=0.39t \\ 38.45=0.39t \\ (38.45)/(0.39)=t \\ \\ 98.58=t \end{gathered}`

You can talk approximately 98.6 minutes for $35