Question

A phone company offers two monthly plans. Plan A costs $26 plus an additional $0.11 for each minute of calls. Plan B costs $16 plus an additional $0.16 for each minute of calls.

For what amount do the two callings costs the same? __ minutes

What is the cost when the two plans cost the same?

Answer 1

Function for the cost of using Plan A: Ca(x) = $26 + ($0.11/min)x

Function for the cost of using Plan A: Ca(x) = $16 + ($0.11/min)x

After how many minutes would the costs be equal? Set these two expressions equal to one another and solve the resulting equation for x:

$26 + ($0.11/min)x

Cb(x) = $16 + ($0.16/min)x = $26 + ($0.11/min)x

To solve this for x, subtract $16 from both sides:

($0.16/min)x = $10 + ($0.11/min)x

Combining like terms: ($0.05/min)x = $10.

Dividing both sides by ($0.05/min): x = ($10) / ($0.05/min) = 200

After 200 minutes, the costs of the two services would become the same, but would not stay the same.

Answer 2

If you want to find x=minutes you set both equations =to each other. Then plug in x=the minutes you found isolating x, and you’ll find your value.