A project can be completed by team A in 12 days and by team B in 15 days. After 3 days of cooperation between the two teams, what fraction of the project is left?
一项工程，由甲队独做需要12天完成，乙队独做需15天完成．现由两队合作3天后，还剩工程的几分之几？
<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">(3/20) * 3</gadget>
<output>9/20 = around 0.45</output>

<gadget id="calculator">1 - (9/20)</gadget>
<output>11/20 = around 0.55</output>

<result>11/20 = around 0.55</result>