Answer:
80 minutes
Step-by-step explanation:
Represent Plan A as y = $26.50 + ($0.35/min)x, where x is the number of minutes consumed.
Represent Plan A as y = $42.50 + ($0.15/min)x
We set these two equations equal to one another and solve for x, the number of minutes at which the costs of the two plans are momentarily equal:
y = $26.50 + ($0.35/min)x = y = $42.50 + ($0.15/min)x
Combining like terms, we get: ($0.20/min)x = $16.00
$16.00
Then x = -------------------- = 80 minutes
($0.20/min)
