SOLUTION: I have a big test and cannot firqure this out please help A cellular phone company offers a contract for which the cost C, in dollars, of T minutes of telephoning is given by C=0.

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Question 574818: I have a big test and cannot firqure this out please help
A cellular phone company offers a contract for which the cost C, in dollars, of T minutes of telephoning is given by C=0.25(t-600)+50.95, where it is assumed that t is greater then or equal to 600 minutes. What time keeps the cost between $97.95 and $123.45?

for the cost to be between 97.95 and 123.45 the time must be between and minutes
Answer by stanbon(75887) (Show Source):
You can put this solution on YOUR website!
C=0.25(t-600)+50.95, where it is assumed that t is greater then or equal to 600 minutes. What time keeps the cost between $97.95 and $123.45?
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97.95 <= 0.25(t-600)+50.95 <= 123.45
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Subtract 50.95 along the line:
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45 <= 0.25(t-600) <=72.50
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Divide through by 0.25 to get:
180 <= t-600 <= 290
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Add 600 along the line:
780 <= t <=890
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Cheers,
Stan H.
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