There is a batch of goods in a certain warehouse. If 3 large trucks are used, it can be shipped in 4 days; if 4 small trucks are used, it can be shipped in 5 days; if 20 pallet trucks are used, it can be shipped in 6 days. Now use 2 large trucks, 3 small trucks and 7 scooters to transport together for 2 days, and then switch to scooters for transportation. The transportation must be completed within two days, so how many scooters are needed every day for the next two days.
某仓库内有一批货物，如果用3辆大卡车，4天可以运完；如果用4辆小卡车，5天可以运完；如果用20辆板车，6天可以运完．现在先用2辆大卡车，3辆小卡车和7辆板车共同运2天后，全部改用板车运，必须在两天内运完，那么后两天每天至少需要多少辆板车．
<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">(1/4) / 3</gadget>
<output>1/12 = around 0.083333</output>

<gadget id="calculator">(1/12) * 2</gadget>
<output>1/6 = around 0.166667</output>

<gadget id="calculator">1 / 5</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">(1/5) / 4</gadget>
<output>1/20 = around 0.05</output>

<gadget id="calculator">(1/20) * 3</gadget>
<output>3/20 = around 0.15</output>

<gadget id="calculator">1 / 6</gadget>
<output>1/6 = around 0.166667</output>

<gadget id="calculator">(1/6) / 20</gadget>
<output>1/120 = around 0.008333</output>

<gadget id="calculator">(1/120) * 7</gadget>
<output>7/120 = around 0.058333</output>

<gadget id="calculator">(1/6) + (3/20) + (7/120)</gadget>
<output>3/8 = around 0.375</output>

<gadget id="calculator">(3/8) * 2</gadget>
<output>3/4 = around 0.75</output>

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

<gadget id="calculator">(1/4) / 2 / (1/120)</gadget>
<output>15</output>

<result>15</result>