To build a road, A completed it in 10 days alone, and B completed it in 8 days alone. A repaired it for a few days first, and A and B completed the entire task in the remaining two days. How many days did A repair it first?
修一条路，甲单独修10天完成，乙单独修8天完成，甲先修了若干天，剩下的甲、乙合修两天完成全部任务，甲先修了多少天？
<gadget id="calculator">1 / 10</gadget>
<output>1/10 = around 0.1</output>

<gadget id="calculator">1 / 8</gadget>
<output>1/8 = around 0.125</output>

<gadget id="calculator">(1/10) + (1/8)</gadget>
<output>9/40 = around 0.225</output>

<gadget id="calculator">(9/40) * 2</gadget>
<output>9/20 = around 0.45</output>

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

<gadget id="calculator">(11/20) / (1/10)</gadget>
<output>11/2 = around 5.5</output>

<result>11/2 = around 5.5</result>