A student reads (1/5) of the pages of a book on the first day, and reads 15 pages on the second day. At this time, the ratio of the number of pages he has read to the number of pages he has not read is 2:3. How many pages are there?
某学生第一天看了一本书页数的(1/5)，第二天看了15页，这时已看的页数与未看的页数之比是2：3，这本书共有多少页？
<gadget id="calculator">3 + 2</gadget>
<output>5</output>

<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">1 / 5</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">(2/5) - (1/5)</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">15 / (1/5)</gadget>
<output>75</output>

<result>75</result>