For a project, team A alone completes the task in 12 days, team B alone completes the task in 15 days, team A alone completes (1/4), and the rest is done jointly by A and B. How many days will it take to complete the task?
一件工程，甲队独做12天完成任务，乙队独做15天完成任务，甲队单独完成了(1/4)，剩下的由甲、乙合做，还要几天完成任务？
<gadget id="calculator">1 / 4</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 / 12</gadget>
<output>1/12 = around 0.083333</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>

<result>5</result>