Xiaohong read the whole book (1/10) on the first day, 35 pages on the second day, and 7 pages on the second day. She read exactly 40% of the whole book in two days. How many pages does the book have?
小红第一天读了全书的(1/10)，第二天读了35页，再读7页，两天恰好读了全书的40%，这本书一共有多少页．
<gadget id="calculator">35 + 7</gadget>
<output>42</output>

<gadget id="calculator">40 / 100</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">1 / 10</gadget>
<output>1/10 = around 0.1</output>

<gadget id="calculator">(2/5) - (1/10)</gadget>
<output>3/10 = around 0.3</output>

<gadget id="calculator">42 / (3/10)</gadget>
<output>140</output>

<result>140</result>