pile of coal is originally planned to burn 0.6 tons per day, and it will be burned in 30 days; it will actually burn 0.5 tons per day, how many days will it actually burn? (proportional solution)
一堆煤原计划每天烧0.6吨，30天烧完；实际每天烧0.5吨，实际多少天烧完？(比例解)
<gadget id="calculator">0.6 * 30</gadget>
<output>18</output>

<gadget id="calculator">18 / 0.5</gadget>
<output>36</output>

<result>36</result>