A project can be completed in 3 days for A and 5 days for B (5/14); if it takes 5 days for A, it can be completed in 3 days for B (3/14). So how many days does it take for A and B to cooperate to complete the task?
一件工程，甲干3天，乙干5天可完成(5/14)；若甲干5天，乙干3天可完成(3/14)．那么甲乙合作需多少天才能完成任务．
<gadget id="calculator">5 / 14</gadget>
<output>5/14 = around 0.357143</output>

<gadget id="calculator">3 / 14</gadget>
<output>3/14 = around 0.214286</output>

<gadget id="calculator">(5/14) + (3/14)</gadget>
<output>4/7 = around 0.571429</output>

<gadget id="calculator">(4/7) / 8</gadget>
<output>1/14 = around 0.071429</output>

<gadget id="calculator">1 / (1/14)</gadget>
<output>14</output>

<result>14</result>