A 6-meter-long iron wire uses up 2.4 meters for the first time and 1.5 meters for the second time. How many meters is the rest shorter than the original?
一根6米长的铁丝，第一次用去2.4米，第二次用去1.5米．剩下的比原来短了多少米？
<gadget id="calculator">2.4 + 1.5</gadget>
<output>3.9</output>

<result>3.9</result>