Xiaoxiao read the book. I read (3/7) on the first day, and I read the whole book less (1/7) on the second day than on the first day. What percentage of the book was read in the two days?
笑笑看书，第一天看了(3/7)，第二天比第一天少看全书的(1/7)，两天一共看了几分之几？
<gadget id="calculator">3 / 7</gadget>
<output>3/7 = around 0.428571</output>

<gadget id="calculator">1 / 7</gadget>
<output>1/7 = around 0.142857</output>

<gadget id="calculator">(3/7) - (1/7)</gadget>
<output>2/7 = around 0.285714</output>

<gadget id="calculator">(3/7) + (2/7)</gadget>
<output>5/7 = around 0.714286</output>

<result>5/7 = around 0.714286</result>