SOLUTION: Matt wants to call his mother long distance. The rate is 80 cents for the first three minutes and 20 cents for each additional minute. How long can he talk for 3.00 dollars.
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Question 825595: Matt wants to call his mother long distance. The rate is 80 cents for the first three minutes and 20 cents for each additional minute. How long can he talk for 3.00 dollars.
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c = 20t + 80
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interpretation of the equation: c = 20t + 80
c is the cost to talk for (t+3) minutes, where t is the talking-time in minutes
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c = 20t + 80
c - 80 = 20t
t = (c - 80)/20
t = (300 - 80)/20
t = 11 minutes
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from the definition:
c (300 cents in this case), is the cost to talk for (t+3) minutes
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answer:
can talk for a total of (t+3) or 14 minutes
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