10

Set 5: Linear Equations (Advanced)

Explanation

Answer: D

A car rental agency charges $30 per day plus $0.50 per mile. If you rent a car for one day and the total cost is $55, how many miles did you drive?

A.

170

B.

12.5

C.

25

D.

50

✓ Correct

Detailed Explanation

Choice D is correct. Choice C is the correct answer. We model this with 0.50x+30=550.50x + 30 = 55, where xx is miles. 1. Set up equation: 0.50x+30=550.50x + 30 = 55 2. Subtract 30 from both sides: 0.50x=55300.50x = 55 - 30 3. Simplify: 0.50x=250.50x = 25 4. Divide both sides by 0.50: x=250.50x = \frac{25}{0.50} 5. Simplify: x=50x = 50 6. Verify: 0.50(50)+30=25+30=550.50(50) + 30 = 25 + 30 = 55 ✓ So, you drove 50 miles. Choice C is incorrect because this results from adding 30 to 55: 8585, then dividing by 0.50: 170170. You subtract the daily rate. Choice D is incorrect because this is the cost of the mileage (25),notthenumberofmiles.ChoiceBisincorrectbecausethisresultsfrommultiplying25by0.50:12.25), not the number of miles. Choice B is incorrect because this results from multiplying 25 by 0.50: 12.5$. You need to divide.

Key Steps:

The correct answer is 50

Why others are wrong:
A: Choice A is incorrect and may result from a calculation error.
B: Choice B is incorrect and may result from a calculation error.
C: Choice C is incorrect and may result from a calculation error.

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