The credit remaining on a phone card (in dollars) is a linear function of the total calling time made with the card (in minutes), The remaining credit after 38 minutes of calls is 520.44, and the...

Extracted text: The credit remaining on a phone card (in dollars) is a linear function of the total calling time made with the card (in minutes), The remaining credit after 38 minutes of calls is 520.44, and the remaining credit after 69 minutes of calls is S16.72. What is the remaining credit after 77 minutes of calls? Remaining credit (in dollars) Calling time (In minutes)