Assume that A needs 3 days to complete half of a certain job, and B needs 4 days to complete one-third of a certain job. Now that A and B are working together, how many days will it take to complete this job.
设A需3天完成某工作的一半，B需4天完成某项工作的三分之一，现在A和B合做，需多少天完成此项工作．
<gadget id="calculator">1 / 2</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">(1/2) / 3</gadget>
<output>1/6 = around 0.166667</output>

<gadget id="calculator">1 / 3</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">(1/3) / 4</gadget>
<output>1/12 = around 0.083333</output>

<gadget id="calculator">(1/6) + (1/12)</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">1 / (1/4)</gadget>
<output>4</output>

<result>4</result>