A wire uses half of its total length for the first time, and the remaining half for the second time, leaving 20 meters. How long is this wire originally?
一根电线第一次用去全长的一半，第二次用去余下的一半，还剩下20米．这根电线原来长多少米？
<gadget id="calculator">20 * 2 * 2</gadget>
<output>80</output>

<result>80</result>