To build a road, team A completed it alone in 15 days, and team B completed it in 12 days. After the two teams jointly repaired it in 4 days, B was transferred away, and team A continued to complete the rest of the road. How many days did Team A practice together?
修一条公路，甲队独修15天完成，乙队独修12天完成，两队合修4天后乙调走，剩下的路由甲队继续修完．甲队共修了多少天？
<gadget id="calculator">1 / 12</gadget>
<output>1/12 = around 0.083333</output>

<gadget id="calculator">(1/12) * 4</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">1 - (1/3)</gadget>
<output>2/3 = around 0.666667</output>

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

<gadget id="calculator">(2/3) / (1/15)</gadget>
<output>10</output>

<result>10</result>