6 excavators work 5 hours a day to dig a ditch 100 meters long, 15 meters wide and 3 meters deep in 10 days; 10 excavators work 8 hours a day to dig a trench 150 meters long, 20 meters wide and 3 meters deep How many days does it take for a ditch of 4 meters?
6台挖土机每天工作5小时，挖长100米，宽15米，深3米的一条沟用10天；10台挖土机，每天工作8小时，挖长150米，宽20米，深4米的一条沟，需要多少天．
<gadget id="calculator">3 / 10 / 6 / 5</gadget>
<output>1/100 = around 0.01</output>

<gadget id="calculator">100 * 15 * (1/100) * 10</gadget>
<output>150</output>

<gadget id="calculator">4 / 150 / 8</gadget>
<output>1/300 = around 0.003333</output>

<gadget id="calculator">150 * 20 * (1/300)</gadget>
<output>10</output>

<result>10</result>