There are two jobs, A and B, and it takes Master Zhang 9 days to complete job A alone, and 12 days to complete job B alone. It takes Master Wang 3 days to complete task A alone, and 15 days to complete task B alone. If two people cooperate to complete these two tasks, how many days is the minimum required?
有甲、乙两项工作，张师傅单独完成甲工作要9天，单独完成乙工作要12天．王师傅单独完成甲工作要3天，单独完成乙工作要15天．如果两人合作完成这两项工作，最少需要多少天？
<gadget id="calculator">1 / 12</gadget>
<output>1/12 = around 0.083333</output>

<gadget id="calculator">(1/12) * 3</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">1 - (1/4)</gadget>
<output>3/4 = around 0.75</output>

<gadget id="calculator">1 / 15</gadget>
<output>1/15 = around 0.066667</output>

<gadget id="calculator">(1/12) + (1/15)</gadget>
<output>3/20 = around 0.15</output>

<gadget id="calculator">(3/4) / (3/20)</gadget>
<output>5</output>

<gadget id="calculator">3 + 5</gadget>
<output>8</output>

<result>8</result>