Xiao Ming reads a book on the first day (1/5). If he reads another 120 pages, the ratio of the number of pages he has read to the number of pages he has not read is 3:2. How many pages is this book?
小明看一本书，第一天看了(1/5)，如果再看120页，这时已看的页数与未看页数的比是3：2，这本书多少页？
<gadget id="calculator">3 + 2</gadget>
<output>5</output>

<gadget id="calculator">3 / 5</gadget>
<output>3/5 = around 0.6</output>

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

<gadget id="calculator">(3/5) - (1/5)</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">120 / (2/5)</gadget>
<output>300</output>

<result>300</result>