Congcong and his mother made a big cake together. Congcong ate (2/5) of the whole cake, and his mother ate (1/5) of the whole cake. How much of the whole cake did they eat?
聪聪和妈妈一起做了一个大蛋糕，聪聪吃了整个蛋糕的(2/5)，妈妈吃了整个蛋糕的(1/5)，他们两人吃了整个蛋糕的几分之几？
<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">1 / 5</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">(2/5) + (1/5)</gadget>
<output>3/5 = around 0.6</output>

<result>3/5 = around 0.6</result>