A piece of rectangular paper, (3/7) is used the first time, and the same amount is used the second time. How much of this paper is used twice?
一张长方形纸，第一次用去它的(3/7)，第二次用去的与第一次同样多．两次一共用去这张纸的几分之几？
<gadget id="calculator">3 / 7</gadget>
<output>3/7 = around 0.428571</output>

<gadget id="calculator">(3/7) + (3/7)</gadget>
<output>6/7 = around 0.857143</output>

<result>6/7 = around 0.857143</result>