Question

MaineCellular offers a phone plan that costs $12 per month plus 10 cents per minute. Portland Wireless offers a plan that costs $20 per month plus 5 cents per minute. How many minutes could you use in a month so that it would cost less to use the MaineCellular plan? Be specific in your answer - give the full range of minutes that answers the question.

Answer 1

X = the cost of MaineCellular's plan
P = the cost of Portland Wireless' plan
T = time in minutes.

X = $12 + $0.10 T
P = $20 + $0.05 T

P = X at the number of minutes that the two costs cross. So, set X = P

$12 + $0.10 T = $20 + $0.05 T

Solve for T.

Once you have T, anything less than T minutes will give one of the plans an edge. Which one?

Anything greater than T minutes will give the other plan the edge.