Xiaoqiang planned to read an extracurricular book in 3 days (the same number of pages per day). The first day went according to the original plan, but the second day was due to a class reunion, and he only read 50 pages. In this way, he just read it two days ago. half of the book. How many pages does this extracurricular book have? (answer in two ways)
小强计划用3天看完一本课外书(每天看的页数一样)，第一天按原计划进行，第二天因同学聚会，只看了50页，这样，他前两天正好看了全书的一半．这本课外书有多少页？(用两种方法解答)
<gadget id="calculator">1 / 2</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">1 / 3</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">(1/2) - (1/3)</gadget>
<output>1/6 = around 0.166667</output>

<gadget id="calculator">50 / (1/6)</gadget>
<output>300</output>

<result>300</result>