When Xiao Ming reads a book, he reads (1/7) of the total pages on the first day, reads 28 pages on the second day, and starts from page 49 on the third day. How many pages does this book have in total?
小明看一本书，第一天看了总页数的(1/7)，第二天看了28页，第三天应从第49页读起，这本书总共有多少页？
<gadget id="calculator">49 - 1 - 28</gadget>
<output>20</output>

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

<gadget id="calculator">20 / (1/7)</gadget>
<output>140</output>

<result>140</result>