A job alone takes 9 hours and B alone takes 12 hours. If A, B, A, B... take turns to work in the order, and each person works for 1 hour each time, how much time will it take to complete this work?
一项工作，甲单独完成要9小时，乙单独完成要12小时．如果按照甲、乙、甲、乙…的顺序轮流工作，每人每次工作1小时，那么完成这项工作要多少时间？
<gadget id="calculator">1 / 9</gadget>
<output>1/9 = around 0.111111</output>

<gadget id="calculator">1 / 12</gadget>
<output>1/12 = around 0.083333</output>

<gadget id="calculator">(1/9) + (1/12)</gadget>
<output>7/36 = around 0.194444</output>

<gadget id="calculator">(7/36) * 5</gadget>
<output>35/36 = around 0.972222</output>

<gadget id="calculator">1 - (35/36)</gadget>
<output>1/36 = around 0.027778</output>

<gadget id="calculator">(1/36) / (1/9)</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">10 + (1/4)</gadget>
<output>41/4 = around 10.25</output>

<result>41/4 = around 10.25</result>