A wire, cut off 12 sections of the same length, each section is 21 meters long, leaving 36 meters. How long was the wire originally?
一根电线，剪去同样长的12段，每段长21米，还剩下36米．这根电线原来有多长？
<gadget id="calculator">21 * 12</gadget>
<output>252</output>

<gadget id="calculator">252 + 36</gadget>
<output>288</output>

<result>288</result>