A watermelon, father ate (2/9) of this watermelon, mother ate (1/9) 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(2/9)，妈妈吃了这个西瓜的(1/9)，两人一共吃了这个西瓜的几分之几？
<gadget id="calculator">2 / 9</gadget>
<output>2/9 = around 0.222222</output>

<gadget id="calculator">1 / 9</gadget>
<output>1/9 = around 0.111111</output>

<gadget id="calculator">(2/9) + (1/9)</gadget>
<output>1/3 = around 0.333333</output>

<result>1/3 = around 0.333333</result>