The apples in the market sell (1/7) of the total in the first week, and (2/7) of the total in the second week. What fraction of the total number of apples were sold in these two weeks? What fraction is left?
商场的苹果，第一周卖掉总数的(1/7)，第二周卖掉总数的(2/7)．这两周共卖掉苹果总数的几分之几？还剩几分之几？
<gadget id="calculator">3 / 7</gadget>
<output>3/7 = around 0.428571</output>

<gadget id="calculator">1 - (3/7)</gadget>
<output>4/7 = around 0.571429</output>

<result>4/7 = around 0.571429</result>