Xiaolan used up 3.7 meters of rope, and the rest was 1.3 meters less than what was used. How long is this rope?
小兰一根绳子用去了3.7米，剩下的比用去的少1.3米．这根绳子原来有多长？
<gadget id="calculator">3.7 - 1.3</gadget>
<output>2.4</output>

<gadget id="calculator">2.4 + 3.7</gadget>
<output>6.1</output>

<result>6.1</result>