Students in two groups watered the flowers, the first group watered (2/7) of the total flowers, the second group watered (4/7) of the total flowers, the two groups watered the total number of flowers.
两个小组同学浇花，第一组浇了总花数的(2/7)，第二组浇了总花数的(4/7)，两个组一共浇了总花数的多少．
<gadget id="calculator">2 / 7</gadget>
<output>2/7 = around 0.285714</output>

<gadget id="calculator">4 / 7</gadget>
<output>4/7 = around 0.571429</output>

<gadget id="calculator">(2/7) + (4/7)</gadget>
<output>6/7 = around 0.857143</output>

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