A piece of cake, Xiaoming ate (1/8), Xiaohong ate (3/8), how much of this cake is left?
块蛋糕，小明吃了(1/8)，小红吃了(3/8)了，这块蛋糕还剩几分之几？
<gadget id="calculator">1 / 8</gadget>
<output>1/8 = around 0.125</output>

<gadget id="calculator">3 / 8</gadget>
<output>3/8 = around 0.375</output>

<gadget id="calculator">(1/8) + (3/8)</gadget>
<output>1/2 = around 0.5</output>

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

<result>1/2 = around 0.5</result>