5

Set 11: Linear Functions (Intermediate)

Explanation

Answer: A

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

A.

150150

✓ Correct
B.

1515

C.

550550

D.

100100

Detailed Explanation

Choice A is correct. Choice A is the correct answer. Solve for x. 1. Model: C=0.10x+40C = 0.10 x + 40. 2. Substitute: 55=0.10x+4055= 0.10 x + 40. 3. Subtract 40: 15=0.10x15= 0.10 x. 4. Divide: x=15/0.10=150x = 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 150150

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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