Mom bought a cake, Xiao Ming ate (1/4), Dad ate (1/2), how much is left?
妈妈买来一个蛋糕，小明吃了(1/4)，爸爸吃了(1/2)，还剩下多少？
<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">1 / 2</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">1 - (1/4) - (1/2)</gadget>
<output>1/4 = around 0.25</output>

<result>1/4 = around 0.25</result>