4 sets of the same mower can mow 4.2 hectares in 5 hours. According to this calculation, how many hectares does a lawnmower mow in one hour?
4台同样的割草机，5小时割草4.2公顷．照这样计算，一台割草机一小时割草多少公顷？
<gadget id="calculator">4.2 / 4 / 5</gadget>
<output>0.21</output>

<result>0.21</result>