It takes 12 days for team A to complete a project alone, and 15 days for team B. After the two teams cooperate for a certain number of days, there is still (1/4) of the project left. How many days did the two teams cooperate?
单独完成一项工程，甲队要12天，乙队要15天，两队合作若干天后，还剩工程的(1/4)，两队合作了多少天？
<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>