Question 318021
cost=0.25(t-500)+$49.95 cell phone contract. It is assumed that t>/500 minutes. For the cost to be between $97.20 and $121.95, the telephone time must be between
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Solve: 97.20 < 0.25(t-500)+$49.95 < 121.95
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Subtract 49.95 along the line:
47.20 < 0.25(t-500) < 72
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Divide by 0.25 along the line:
188.80 < t-500 < 288
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Add 500 along the line:
688.80 < t < 788
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Cheers,
Stan H.
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