birthday cake, Xiaojun ate (2/5), ate more of this cake than his mother (1/10), and the rest of his father ate, how much of this cake did his father eat?
一个生日蛋糕，小军吃了(2/5)，比妈妈多吃了这个蛋糕的(1/10)，其余的爸爸吃了，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 / 10</gadget>
<output>1/10 = around 0.1</output>

<gadget id="calculator">(2/5) - (1/10)</gadget>
<output>3/10 = around 0.3</output>

<gadget id="calculator">1 - (3/10) - (2/5)</gadget>
<output>3/10 = around 0.3</output>

<result>3/10 = around 0.3</result>