Question 353356: A long distance telephone call using Down East Calling costs 10 cents for the first minute and 8 cnts for each additional minute. The same call on Long Call Systems costs, 16 cents for the first minute and 6 cent for each additional minute. For what length phone calls is Down East Calling less expensive:
Answer by stanbon(75887)   (Show Source):
You can put this solution on YOUR website! A long distance telephone call using Down East Calling costs 10 cents for the first minute and 8 cents for each additional minute.
D(x) = 10 + 8(x-1)
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The same call on Long Call Systems costs, 16 cents for the first minute and 6 cent for each additional minute.
L(x) = 16 + 6(x-1)
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For what length phone calls is Down East Calling less expensive:
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Solve D(x) < L(x) for "x":
10+8(x-1) < 16+6(x-1)
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10+8x-8 < 16+6x-6
2+8x < 10+6x
2x < 8
x < 4 minutes
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Cheers,
Stan H.
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