Question

select the correct answer.

the perimeter of a rectangle is 42 inches. if the width of the rectangle is 6 inches, what is the length?

12 inches
15 inches
21 inches
40 inches

Explanation:

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"new_concepts": [
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</pre_analysis>

<reasoning>

Set up the perimeter equation

\[

$$\begin{aligned} &P = 2(l + w) \\ &P = 42 \\ &w = 6 \end{aligned}$$

\]

Substitute and solve for length

\[

$$\begin{aligned} &42 = 2(l + 6) \\ &21 = l + 6 \\ &l = 15 \end{aligned}$$

\]
</reasoning>

<answer>
<mcq-option>12 inches</mcq-option>
<mcq-correct>15 inches</mcq-correct>
<mcq-option>21 inches</mcq-option>
<mcq-option>40 inches</mcq-option>
</answer>

<post_analysis>
{
"subject": "Mathematics",
"question_type": "Multiple Choice",
"knowledge_point": [
"Mathematics",
"Geometry",
"Perimeter of a Rectangle"
]
}
</post_analysis>

Answer:

<pre_analysis>
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"step_cot",
"multiple_choice_formatter",
"explain_then_answer",
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],
"new_concepts": [
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],
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]
}
</pre_analysis>

<reasoning>

Set up the perimeter equation

\[

$$\begin{aligned} &P = 2(l + w) \\ &P = 42 \\ &w = 6 \end{aligned}$$

\]

Substitute and solve for length

\[

$$\begin{aligned} &42 = 2(l + 6) \\ &21 = l + 6 \\ &l = 15 \end{aligned}$$

\]
</reasoning>

<answer>
<mcq-option>12 inches</mcq-option>
<mcq-correct>15 inches</mcq-correct>
<mcq-option>21 inches</mcq-option>
<mcq-option>40 inches</mcq-option>
</answer>

<post_analysis>
{
"subject": "Mathematics",
"question_type": "Multiple Choice",
"knowledge_point": [
"Mathematics",
"Geometry",
"Perimeter of a Rectangle"
]
}
</post_analysis>