Uncle Li surrounded a rectangular vegetable field with a 61-meter-long fence. If the length of this vegetable field is 19 meters, how many meters is it wide?
李大伯用61米长的篱笆围了一块长方形的菜地，如果这块菜地的长是19米，那么它的宽是多少米？
<gadget id="calculator">61 / 2</gadget>
<output>61/2 = around 30.5</output>

<gadget id="calculator">(61/2) - 19</gadget>
<output>23/2 = around 11.5</output>

<result>23/2 = around 11.5</result>