A certain project can be completed in 50 days alone, and B can be completed in 75 days alone. Now the two are cooperating, but B is away for a few days on the way, and the project is completed 40 days after the start of the project. Then B left halfway how many days.
某一个工程甲单独做50天可以完成，乙单独做75天可以完成，现在两人合作，但途中乙因事离开了几天，从开工后40天把这个工程做完，则乙中途离开了多少天．
<gadget id="calculator">1 / 50</gadget>
<output>1/50 = around 0.02</output>

<gadget id="calculator">(1/50) * 40</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">1 - (4/5)</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">1 / 75</gadget>
<output>1/75 = around 0.013333</output>

<gadget id="calculator">(1/5) / (1/75)</gadget>
<output>15</output>

<gadget id="calculator">40 - 15</gadget>
<output>25</output>

<result>25</result>