Use a rope to measure the depth of the well. If the rope is folded in half, it will be 8 meters outside the well, and if the rope is folded in three, it will be 1 meter outside the well. How deep is the well? Use equations and formulas in two ways.
用绳子量井的深度，将绳子2折则多出井外8米，将绳子3折则多出井外1米．井深多少米？用方程和算式两种方法．
<gadget id="calculator">2 * 8</gadget>
<output>16</output>

<gadget id="calculator">1 * 3</gadget>
<output>3</output>

<gadget id="calculator">16 - 3</gadget>
<output>13</output>

<gadget id="calculator">3 - 2</gadget>
<output>1</output>

<gadget id="calculator">13 / 1</gadget>
<output>13</output>

<result>13</result>