birthday cake, Xiaohua ate the cake (1/8), mother ate the cake (2/8), father and mother ate the same amount, how much of the birthday cake did the three eat together
一个生日蛋糕，小华吃了蛋糕的(1/8)，妈妈吃了蛋糕的(2/8)，爸爸跟妈妈吃得同样多，三人一共吃了这个生日蛋糕的多少
<gadget id="calculator">1 / 8</gadget>
<output>1/8 = around 0.125</output>

<gadget id="calculator">2 / 8</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">(1/8) + (1/4) + (1/4)</gadget>
<output>5/8 = around 0.625</output>

<result>5/8 = around 0.625</result>