A tractor originally planned to plow a piece of land of 7.2 hectares in 9 hours. Actually plowed 0.1 hectare more than planned per hour. How many hours did it actually take to plow this land?
一台拖拉机原计划用9小时耕完7.2公顷的一块地．实际每小时比计划多耕0.1公顷，耕完这块地实际用了几小时？
<gadget id="calculator">7.2 / 9</gadget>
<output>0.8</output>

<gadget id="calculator">0.8 + 0.1</gadget>
<output>0.9</output>

<gadget id="calculator">7.2 / 0.9</gadget>
<output>8</output>

<result>8</result>