A piece of land (9/20) hectares can be plowed by 3 tractors in (3/5) hours. On average, how many hectares of land is plowed per tractor per hour?
一块地(9/20)公顷，用3台拖拉机来耕，(3/5)小时可以耕完．平均每台拖拉机每小时耕地多少公顷？
<gadget id="calculator">9 / 20</gadget>
<output>9/20 = around 0.45</output>

<gadget id="calculator">3 / 5</gadget>
<output>3/5 = around 0.6</output>

<gadget id="calculator">(9/20) / 3 / (3/5)</gadget>
<output>1/4 = around 0.25</output>

<result>1/4 = around 0.25</result>