If a pile of coal burns 1.2 tons per day as planned, it can be burned for 15 days, but the actual daily burn is 25% less than the original plan. How many days can this pile of coal be burned?
一堆煤，如果按计划每天烧1.2t，可以烧15天，实际每天比原计划少烧25%，这堆煤可以烧多少天？
<gadget id="calculator">1.2 * 15</gadget>
<output>18</output>

<gadget id="calculator">25 / 100</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">1 - (1/4)</gadget>
<output>3/4 = around 0.75</output>

<gadget id="calculator">1.2 * (3/4)</gadget>
<output>0.9</output>

<gadget id="calculator">18 / 0.9</gadget>
<output>20</output>

<result>20</result>