A cake, the first time I ate the whole cake (2/9), and the second time I ate the whole cake (3/9), what fraction of the cake is left?
一个蛋糕，第一次吃了整个蛋糕的(2/9)，第二次吃了整个蛋糕的(3/9)，这个蛋糕还剩几分之几？
<gadget id="calculator">2 / 9</gadget>
<output>2/9 = around 0.222222</output>

<gadget id="calculator">3 / 9</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">(2/9) + (1/3)</gadget>
<output>5/9 = around 0.555556</output>

<gadget id="calculator">1 - (5/9)</gadget>
<output>4/9 = around 0.444444</output>

<result>4/9 = around 0.444444</result>