Xiao Ming reads a book, he reads (2/5) of the whole book on the first day, and (1/7) of the whole book on the second day, how much is the whole book read in two days?
小明看一本书，第一天看了全书的(2/5)，第二天看了全书的(1/7)，两天共看全书的多少．
<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

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

<gadget id="calculator">(2/5) + (1/7)</gadget>
<output>19/35 = around 0.542857</output>

<result>19/35 = around 0.542857</result>