Two teams, A and B, work together to do a job. Team A takes 6 hours to do it alone, and Team B takes 9 hours to do it alone.
甲乙两队合做一件工作，甲队独做要6小时，乙队独做要9小时，两队每小时完成这份工作的多少．
<gadget id="calculator">1 / 6</gadget>
<output>1/6 = around 0.166667</output>

<gadget id="calculator">1 / 9</gadget>
<output>1/9 = around 0.111111</output>

<gadget id="calculator">(1/6) + (1/9)</gadget>
<output>5/18 = around 0.277778</output>

<result>5/18 = around 0.277778</result>