SOLUTION: 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 30 minutes of calls is

Algebra ->  Linear-equations -> SOLUTION: 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 30 minutes of calls is       Log On


   

Question 1147333: 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 30 minutes of calls is $16.10, and the remaining credit after 59 minutes of calls is $12.33. What is the remaining credit after 79 minutes of calls?
Answer by josgarithmetic(39617) About Me  (Show Source):
You can put this solution on YOUR website!
points (30, 16.1) & (59, 12.33)

y-16.1=%28%2812.33-16.1%29%2F%2859-30%29%29%28x-30%29
y=%28%2812.33-16.1%29%2F%2859-30%29%29%28x-30%29%2B16.1
Simplify the formula.

Let x be 79 and evaluate y to answer the question.