A rope is used up by 1.5 meters, and the remaining is 2.1 meters more than what was used. How many meters was the rope originally?
一根绳子用去了1.5米，剩下的比用去的多2.1米，这根绳子原来有多少米？
<gadget id="calculator">1.5 + 2.1 + 1.5</gadget>
<output>5.1</output>

<result>5.1</result>