It is estimated that the broad-leaved forest can release 2.19 tons of oxygen in 3 days. How many tons of oxygen can be released in a month according to this calculation? (based on 30 days)
据测算阔叶林3天可以放出氧气2.19吨，照这样计算一个月可以放出多少吨氧气？(以30天计)
<gadget id="calculator">2.19 / 3</gadget>
<output>0.73</output>

<gadget id="calculator">0.73 * 30</gadget>
<output>21.9</output>

<result>21.9</result>