watermelon, my mother ate this watermelon (2/7), my father ate this watermelon (3/7), I ate the same amount as my mother, what percentage of this watermelon did I eat less than my father?
一个西瓜，妈妈吃了这个西瓜的(2/7)，爸爸吃了这个西瓜的(3/7)，我和妈妈吃的一样多，我比爸爸少吃了这个西瓜的几分之几？
<gadget id="calculator">3 / 7</gadget>
<output>3/7 = around 0.428571</output>

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

<gadget id="calculator">(3/7) - (2/7)</gadget>
<output>1/7 = around 0.142857</output>

<result>1/7 = around 0.142857</result>