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 31 minutes of calls is $20.97, and the remaining credit after 50 minutes of calls is $18.50. What is the remaining credit after 54 minutes of calls?

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Answer:

The credit remaining on a phone card (in dollars) is a linear function of the

total calling time made with the card (in minutes), as shown in the figure below.

The remaining credit after 45 minutes of calls is $22.80 , and the remaining

credit after 64 minutes of calls is $19.76.

Step-by-step explanation:

What is the remaining credit after 73 minutes of calls?

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Not sure what figure you are referring to, write an equation from the given values:

Assign the values as follows

x1 = 45; y1 = 22.80

x2 = 64; y2 = 19.76

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Find the slope (m) using the formula: m = %28y2-y1%29%2F%28x2-x1%29

m = %2819.76-22.80%29%2F%2864-45%29 = %28-3.04%29%2F%2819%29

m = -.16

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