Set 15: Linear Functions (Advanced)

Explanation

Answer: A

A phone plan costs $40 plus $0.10 per text. If the bill was $55, how many texts were sent?

$150$

✓ Correct

$15$

$550$

$100$

Detailed Explanation

Choice A is correct. Choice A is the correct answer. Solve for x. 1. Model: $C = 0.10 x + 40$ . 2. Substitute: $55= 0.10 x + 40$ . 3. Subtract 40: $15= 0.10 x$ . 4. Divide: $x = 15 / 0.10 = 150$ . Strategic Tip: Subtract the fixed cost first, then divide by the rate. Choice B is incorrect because it results from an error in the solution process. Choice C is incorrect because didn't subtract 40. Choice D is incorrect.

Key Steps:

•

The correct answer is $150$

Why others are wrong:

B: Choice B is incorrect and may result from a calculation error.

C: Choice C is incorrect and may result from a calculation error.

D: Choice D is incorrect and may result from a calculation error.

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