The perimeter of a rectangle is 58 decimeters, the length is 17 decimeters, and the width is how many decimeters.
一个长方形的周长是58分米，长是17分米，宽是多少分米．
<gadget id="calculator">58 / 2</gadget>
<output>29</output>

<gadget id="calculator">29 - 17</gadget>
<output>12</output>

<result>12</result>