A shopping mall buys a batch of color TV sets, sells all (1/7) on the first day, sells all (2/7) on the second day, and sells the same amount on the third day as the second day ． What percentage of these color TV sets were sold in the past three days?
商场购进一批彩色电视机，第一天卖出全部的(1/7)，第二天卖出全部的(2/7)，第三天卖出的和第二天卖出的同样多．这三天共卖出这批彩色电视机的几分之几？
<gadget id="calculator">1 / 7</gadget>
<output>1/7 = around 0.142857</output>

<gadget id="calculator">2 / 7</gadget>
<output>2/7 = around 0.285714</output>

<gadget id="calculator">(1/7) + (2/7) + (2/7)</gadget>
<output>5/7 = around 0.714286</output>

<result>5/7 = around 0.714286</result>