There is a pile of coal in a certain factory. It was originally planned to burn 20 tons per day, and it can be burned for 27 days; it actually burned for 30 days, how many tons of coal is actually burned per day? (Solve with ratio)
某工厂有一堆煤，原计划每天烧20吨，可以烧27天；实际烧了30天，实际每天烧煤多少吨？(用比例解)
<gadget id="calculator">20 * 27</gadget>
<output>540</output>

<gadget id="calculator">540 / 30</gadget>
<output>18</output>

<result>18</result>