A project is completed alone, team A takes 50 days, and team B takes 75 days. On the way of the two teams working together, team B rests for a few days, so it takes 40 days to complete. How many days did Team B rest?
一项工程，单独完成，甲队要50天，乙队要75天，两队合做途中，乙队休息几天，这样共用40天完成．乙队休息了多少天？
<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>