Xiaohong reads a book. She reads 30 pages on the first day, and reads the first day (5/6) on the second day. At this time, the total number of pages (10/21) is left. How many pages are there in this book? Page?
小红看一本书，第一天看30页，第二天看的是第一天的(5/6)，这时还剩下总页数的(10/21)，这本书有多少页？
<gadget id="calculator">5 / 6</gadget>
<output>5/6 = around 0.833333</output>

<gadget id="calculator">30 * (5/6)</gadget>
<output>25</output>

<gadget id="calculator">25 + 30</gadget>
<output>55</output>

<gadget id="calculator">10 / 21</gadget>
<output>10/21 = around 0.47619</output>

<gadget id="calculator">1 - (10/21)</gadget>
<output>11/21 = around 0.52381</output>

<gadget id="calculator">55 / (11/21)</gadget>
<output>105</output>

<result>105</result>