Xiaoqiang read a science and technology book, read 20 pages on the first day, 25 pages on the second day, and just read the whole book in two days (3/5). How many pages does this technical book have? (solution by equation)
小强看一本科技书，第一天看了20页，第二天看了25页，两天正好看了全书的(3/5)．这本科技书有多少页？(用方程解)
<gadget id="calculator">20 + 25</gadget>
<output>45</output>

<gadget id="calculator">3 / 5</gadget>
<output>3/5 = around 0.6</output>

<gadget id="calculator">45 / (3/5)</gadget>
<output>75</output>

<result>75</result>