A project can be completed in 50 days alone, and B can be completed in 75 days alone. Now two people are cooperating, but B is away for a few days in the middle due to business, and the project is completed 40 days after the start of work. B left halfway How many days?
一件工程甲独做50天可完，乙独做75天可完，现在两个人合作，但是中途乙因事离开几天，从开工后40天把这件工程做完，问乙中途离开了几天？
<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>