Divide a cake into 5 equal pieces. Xiao Ming ate 3 of them, what fraction of the cake is left?
把一个蛋糕平均分成5块．小明吃了其中的3块，还剩下这个蛋糕的几分之几？
<gadget id="calculator">5 - 3</gadget>
<output>2</output>

<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

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