Set 9: Linear Equations (Advanced)

Explanation

Answer: A

A car travels at $x$ mph for 3 hours and then $x+10$ mph for 2 hours. Total distance is 270 miles. Find $x$ .

✓ Correct

Detailed Explanation

Choice A is correct. Choice D is the correct answer. 1. Equation: $3x + 2(x + 10) = 270$ 2. Simplify: $3x + 2 x + 20 = 270$ 3. Combine: $5x + 20 = 270$ 4. Subtract 20: $5x = 250$ 5. Divide by 5: $x = 50$ 6. Verify: $150+ 120 = 270$ ✓ Choice B is incorrect because it results from an error in the solution process. Choice A is incorrect because it results from an error in the solution process. Choice C is incorrect because it results from an error in the solution process.

Key Steps:

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The correct answer is 50

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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