Xiaohong reads an extracurricular book, and the ratio of the number of pages she has read to the number of pages she has not read is 1:3. If she reads another 24 pages, she can read 40% of the book. How many pages does this extracurricular book have?
小红看一本课外读物，看了的页数与未看的页数比是1：3，如果再看24页，就可以看完全书的40%，这本课外读物一共有多少页？
<gadget id="calculator">40 / 100</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">1 + 3</gadget>
<output>4</output>

<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">(2/5) - (1/4)</gadget>
<output>3/20 = around 0.15</output>

<gadget id="calculator">24 / (3/20)</gadget>
<output>160</output>

<result>160</result>