For a cake, Xiaoli ate (2/5), her mother ate (1/5), and the rest was eaten by her father. How much of the cake did her father eat?
一个蛋糕，小丽吃了(2/5)，妈妈吃了(1/5)，剩下的爸爸吃，爸爸吃了这个蛋糕的几分之几？
<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">1 - (2/5) - (1/5)</gadget>
<output>2/5 = around 0.4</output>

<result>2/5 = around 0.4</result>