A factory has a batch of coal, originally planned to burn 15 tons per day, which can be burned for 80 days. The actual saving is 20% than the original plan every day. How many days can this batch of coal actually be burned?
某厂有一批煤，原计划每天烧15吨，可以烧80天．实际每天比原计划节约20%，这批煤实际可以烧多少天？
<gadget id="calculator">15 * 80</gadget>
<output>1_200</output>

<gadget id="calculator">20 / 100</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">1 - (1/5)</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">15 * (4/5)</gadget>
<output>12</output>

<gadget id="calculator">1_200 / 12</gadget>
<output>100</output>

<result>100</result>