A piece of land has (9/10) square kilometers, and it can be plowed by 20 tractors in (3/4) hours. How many square kilometers does each tractor plow on average per hour?
一块地有(9/10)平方千米，用20台拖拉机耕，(3/4)小时可以耕完，平均每台拖拉机每小时耕地多少平方千米？
<gadget id="calculator">9 / 10</gadget>
<output>9/10 = around 0.9</output>

<gadget id="calculator">3 / 4</gadget>
<output>3/4 = around 0.75</output>

<gadget id="calculator">(9/10) / (3/4) / 20</gadget>
<output>3/50 = around 0.06</output>

<result>3/50 = around 0.06</result>