Zaizai is reading a popular science book. He read 90 pages in the first week. The ratio of the remaining pages to the total number of pages in this book is 1:4. How many pages does this popular science book have?
仔仔正在读一本科普书，第一周读了90页，剩下的页数与这本书总页数的比是1：4，这本科普书一共有多少页？
<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">1 - (1/4)</gadget>
<output>3/4 = around 0.75</output>

<gadget id="calculator">90 / (3/4)</gadget>
<output>120</output>

<result>120</result>