Xiao Ming reads a story book. He read 25% of the whole book on the first day and 35% of the whole book on the second day. He read a total of 84 pages in two days. How many pages does this book have?
小明读一本故事书，第一天读了全书的25%，第二天读了全书的35%，两天共读了84页，这本书一共有多少页？
<gadget id="calculator">25 / 100</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">35 / 100</gadget>
<output>7/20 = around 0.35</output>

<gadget id="calculator">(1/4) + (7/20)</gadget>
<output>3/5 = around 0.6</output>

<gadget id="calculator">84 / (3/5)</gadget>
<output>140</output>

<result>140</result>