Question

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 after33 minutes of calls is $20.05 , and the remaining credit after 67 minutes of calls is $14.95 . What is the remaining credit after 76 minutes of calls?

Answer 1

hmm
so lets make x=# of minutes and y= remaining credit
so we would get points (33,20.05) and (67,14.95)
now lets find slope