Use a rope to measure the depth of the well. Fold the rope in three to measure, and there is 2 feet outside the well; fold the rope in four to measure, and the upper end of the rope is 1 foot from the mouth of the well. How long is the rope?
用绳子测量井深，把绳子三折来测量，井外余2尺；把绳子四折来量，绳子上端距井口还有1尺，求绳子长多少尺？
<gadget id="calculator">3 * 2</gadget>
<output>6</output>

<gadget id="calculator">4 * 1</gadget>
<output>4</output>

<gadget id="calculator">6 + 4</gadget>
<output>10</output>

<gadget id="calculator">4 - 3</gadget>
<output>1</output>

<gadget id="calculator">10 / 1</gadget>
<output>10</output>

<gadget id="calculator">10 + 2</gadget>
<output>12</output>

<gadget id="calculator">12 * 3</gadget>
<output>36</output>

<result>36</result>