A piece of trapezoidal land has an upper base of 600m, a lower base of 1500m, and a height of 120m. If a tractor plows 3.15 hectares per day, how many days can it be plowed?
一块梯形土地上底是600m，下底是1500m，高是120m，用一台每天耕地3.15公顷的拖拉机来耕，几天可以耕完？
<gadget id="calculator">600 + 1_500</gadget>
<output>2_100</output>

<gadget id="calculator">3.15 * 10_000</gadget>
<output>31_500</output>

<gadget id="calculator">120 / 2 / 31_500</gadget>
<output>1/525 = around 0.001905</output>

<gadget id="calculator">2_100 * (1/525)</gadget>
<output>4</output>

<result>4</result>