The cafeteria buys a truckload of coal and plans to use 1.5 tons per day, which can last for 40 days. The actual usage is only 1.2 tons per day, how many days more than planned?
食堂买进一车煤，计划每天用1.5吨，可以用40天．实际每天只用了1.2吨，实际比计划多用多少天？
<gadget id="calculator">40 / 1.2</gadget>
<output>33.333333</output>

<gadget id="calculator">1.5 * 33.333333</gadget>
<output>50</output>

<gadget id="calculator">50 - 40</gadget>
<output>10</output>

<result>10</result>