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A prepaid phone card has a credit of 200 minutes. Write an expression for the number of minutes left on the card after t minutes have been used.

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Answer:


R(t) = 200 - *t

Explanation:

This problem can be modeled by simple decreasing first order function.

This function has the following format


R(t) = R_(0) - a*t

In which R(t) is the remaining time, in minutes,
R_(0) is the initial remaining time, and a is the angular coefficient of the function.

In your problem, the prepaid phone card has a credit of 200 minutes, so
R_(0) = 200. At each minute, the amount of time remaining will decrease by 1, so the angular coefficient is 1, a = 1.

We are left with:


R(t) = 200 - *t

User Emmanuel Rodriguez
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