watermelon, father ate (2/7) of this watermelon, mother ate (3/7) of this watermelon, how much of this watermelon did they eat together?
一个西瓜，爸爸吃了这个西瓜的(2/7)，妈妈吃了这个西瓜的(3/7)，两人一共吃了这个西瓜的几分之几？
<gadget id="calculator">2 / 7</gadget>
<output>2/7 = around 0.285714</output>

<gadget id="calculator">3 / 7</gadget>
<output>3/7 = around 0.428571</output>

<gadget id="calculator">(2/7) + (3/7)</gadget>
<output>5/7 = around 0.714286</output>

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