The power plant shipped a batch of coal, planned to use 30 tons per day, and used it up in 12 days, but actually saved 5 tons of coal per day. How many days more was actually used than planned? (Answer with proportional knowledge)
发电厂运来一批煤，计划每天用30吨，12天用完，实际每天节约5吨煤，实际比计划多用了几天？(用比例知识解答)
<gadget id="calculator">30 * 12</gadget>
<output>360</output>

<gadget id="calculator">30 - 5</gadget>
<output>25</output>

<gadget id="calculator">360 / 25</gadget>
<output>72/5 = around 14.4</output>

<gadget id="calculator">(72/5) - 12</gadget>
<output>12/5 = around 2.4</output>

<result>12/5 = around 2.4</result>