Uncle Wang surrounded the vegetable field twice with a 10.4-meter-long rope, and 6.7 meters were used up. How many meters of rope are left?
王大伯用一根长10.4米长的绳子围了菜地两圈，用去了6.7米，绳子还剩下多少米？
<gadget id="calculator">10.4 - 6.7</gadget>
<output>3.7</output>

<result>3.7</result>