Credit remains on a phone card in dollars is a linear function of a total calling time made with the card in minutes.
The remaining credit after 26 minutes of calls is $26.10 and the remaining credit after 53 minutes of calls is $22.05. What is the remaining credit after 77 minutes of calls?
A word problem is solved using a system of equations. The solution is detailed and well presented. The response received a rating of "5/5" from the student who originally posted the question.