Xiao Ming bought a story book. He read (1/8) of this book on the first day, and (3/8) of this book on the second day. What percentage of this book is left?
小明买了一本故事书．他第一天看了这本书的(1/8)，第二天看了这本书的(3/8)，还剩这本书的几分之几没有看？
<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 - (1/8) - (3/8)</gadget>
<output>1/2 = around 0.5</output>

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