The black hen lays 1 egg and rests for 2 days, and the white hen lays 1 egg and rests for 1 day. The two chickens lay a total of 10 eggs. What is the minimum number of days required?
黑母鸡下1个蛋歇2天，白母鸡下1个蛋歇1天，两只鸡共下10个蛋，最少需要多少天．
<gadget id="calculator">2 + 1 + 1 + 1</gadget>
<output>5</output>

<gadget id="calculator">10 / 5</gadget>
<output>2</output>

<gadget id="calculator">2 * 6</gadget>
<output>12</output>

<gadget id="calculator">12 - 1</gadget>
<output>11</output>

<result>11</result>