A project can be completed by team A in 20 days, team B in 30 days, and team C in 40 days. What should I do if I want to complete it within 15 days?
一项工程，甲队单独做20天完成，乙队单独做30天完成，丙队单独做40天完成．若要在15天内完成，应该怎么办？
<gadget id="calculator">1 / 20</gadget>
<output>1/20 = around 0.05</output>

<gadget id="calculator">(1/20) * 15</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 / 40</gadget>
<output>1/40 = around 0.025</output>

<gadget id="calculator">(1/4) / (1/40)</gadget>
<output>10</output>

<result>10</result>