Take a rectangular wooden board with a length of 26dm, cut off a square with a side length of 3dm at the four corners, and make it into a rectangular open container with a volume of 840dm**2. What is the original width of this wooden board in decimeters?
把一块长26dm的长方形木板，在四个角上分别剪去边长3dm的正方形，将它制成容积为840dm**2的长方形无盖容器，这块木板原来的宽是多少分米？
<gadget id="calculator">3 * 2</gadget>
<output>6</output>

<gadget id="calculator">26 - 6</gadget>
<output>20</output>

<gadget id="calculator">840 / 3 / 20</gadget>
<output>14</output>

<gadget id="calculator">14 + 6</gadget>
<output>20</output>

<result>20</result>