Li Jie reads a story book, read the whole book (1/7) on the first day, and read the whole book (2/7) on the second and third days respectively, what percentage of the whole book is left?
李洁看一本故事书，第1天看了全书的(1/7)，第2、3天各看了全书的(2/7)，还剩下全书的几分之几没有看？
<gadget id="calculator">1 / 7</gadget>
<output>1/7 = around 0.142857</output>

<gadget id="calculator">2 / 7</gadget>
<output>2/7 = around 0.285714</output>

<gadget id="calculator">(1/7) + (2/7) + (2/7)</gadget>
<output>5/7 = around 0.714286</output>

<gadget id="calculator">1 - (5/7)</gadget>
<output>2/7 = around 0.285714</output>

<result>2/7 = around 0.285714</result>