SOLUTION: Suppose that the credit remaining on a phone card (in dollars) is a linear function of the total calling time (in minutes). When graphed, the function gives a line with a slope of

Algebra ->  Coordinate Systems and Linear Equations  -> Linear Equations and Systems Word Problems -> SOLUTION: Suppose that the credit remaining on a phone card (in dollars) is a linear function of the total calling time (in minutes). When graphed, the function gives a line with a slope of       Log On


   

Question 392182: Suppose that the credit remaining on a phone card (in dollars) is a linear function of the total calling time (in minutes). When graphed, the function gives a line with a slope of -0.14. See the figure below.
There is $26.02 in credit remaining on the card after 43 minutes of calls. How much credit was there after 32 minutes of calls?
Answer by stanbon(75887) About Me  (Show Source):
You can put this solution on YOUR website!
Suppose that the credit remaining on a phone card (in dollars) is a linear function of the total calling time (in minutes).
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credit = m(call time) + b
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When graphed, the function gives a line with a slope of -0.14.
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m = -0.14
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See the figure below.
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No figure shown
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There is $26.02 in credit remaining on the card after 43 minutes of calls.
26.02 = -0.14(43) + b
b = 26.02+6.02
b = 32.04
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C(x) = -0.14x+32.04
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How much credit was there after 32 minutes of calls?
C(32) = -0.14(32) + 32.04
C(32) = $27.56
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Cheers,
Stan H.