A batch of coal, calculated by burning 0.4 tons per day according to the plan, can be burned for 50 days. Actually burn 0.25 tons per day, how many days can this batch of coal actually be used for?
一批煤，按计划每天烧0.4吨计算，可烧50天．实际每天烧0.25吨，这批煤实际可用多少天？
<gadget id="calculator">50 / 0.25</gadget>
<output>200</output>

<gadget id="calculator">0.4 * 200</gadget>
<output>80</output>

<result>80</result>