batch of materials is transported from point a to point b, and 20 trucks can complete the transportation in a week. If it is required to complete the transportation in 4 days, how many trucks are needed?
一批物资从a地运到b地，20辆卡车一周可以运完，如果要求4天运完，需要多少辆卡车？
<gadget id="calculator">1 / 20 / 7</gadget>
<output>1/140 = around 0.007143</output>

<gadget id="calculator">(1/140) * 4</gadget>
<output>1/35 = around 0.028571</output>

<gadget id="calculator">1 / (1/35)</gadget>
<output>35</output>

<result>35</result>