2 Mini Lesson: A wireless phone plan costs Eric $35 for a month of service during which he sent 450 text messages. If he was charged a fixed fee of $12.50, how much did he pay per text? Equation: 12.50 + 450t = 35 Explain how each term was determined from the word problem.

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Explanation:

From your knowledge of the world, you know that ...

The problem statement asks for the cost of a single text message. For the purpose of finding that value, it is convenient to represent it using the variable t. The problem statement says Eric was billed for 450 text messages, so we expect his usage-related fee to be 450t, the sum of the costs of 450 messages--using multiplication for the repeated sum.

The problem statement says Eric was billed 12.50 for fixed fees. So, we expect Eric's total bill to be ...

  fixed fees + usage-related fees = 12.50 + 450t

The problem statement says Eric's total bill was 35.00, so we assume that is the sum of the above-listed fees. That is, the two ways to express Eric's total bill are equal.

  12.50 +450t = 35.00