Set 12: Linear Equations

Explanation

Answer: D

A number is doubled, then 5 is added. The result is multiplied by 3 to get 39. What is the number?

✓ Correct

Detailed Explanation

Choice D is correct. Choice A is the correct answer. 1. Equation: $3(2 x + 5) = 39$ 2. Divide by 3: $2x + 5 = 13$ 3. Subtract 5: $2x = 8$ 4. Divide by 2: $x = 4$ 5. Verify: $3(8 + 5) = 39$ ✓ Choice D 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. Choice C is incorrect because it results from an error in the solution process.

Key Steps:

•

The correct answer is 4

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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