A barrel of oil is planned to use 0.25 kg per day, which can be used for 36 days. Actually use 0.2 kg per day, how many days can it be used? (Solve with ratio)
一桶油计划每天用0.25千克，可以用36天．实际每天用0.2千克，可以用多少天？(用比例解)
<gadget id="calculator">0.25 * 36</gadget>
<output>9</output>

<gadget id="calculator">9 / 0.2</gadget>
<output>45</output>

<result>45</result>