10

Set 12: Linear Equations

Explanation

Answer: B

A rectangle's length is 4 cm more than its width. The perimeter is 40 cm. What is the width?

A.

12

B.

8

✓ Correct
C.

16

D.

10

Detailed Explanation

Choice B is correct. Choice D is the correct answer. 1. Define: Width = ww, Length = w+4w + 4. 2. Perimeter: 2(w+4)+2w=402(w + 4) + 2 w = 40 3. Simplify: 2w+8+2w=40→4w+8=402w + 8 + 2 w = 40 \rightarrow 4 w + 8 = 40 4. Subtract 8: 4w=324w = 32 5. Divide by 4: w=8w = 8 6. Verify: Length 12. 2(12)+2(8)=24+16=402(12) + 2(8) = 24 + 16 = 40 ✓ Choice A is incorrect because this is the length. 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.

Key Steps:

•

The correct answer is 8

Why others are wrong:
A: Choice A 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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