book has 600 pages. I read (1/4) of it on the first day and (2/5) of it on the second day. How many pages have I read in total in two days?
一本书600页，第一天看了它的(1/4)，第二天看了它的(2/5)，两天一共看了多少页？
<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

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

<gadget id="calculator">(1/4) + (2/5)</gadget>
<output>13/20 = around 0.65</output>

<gadget id="calculator">600 * (13/20)</gadget>
<output>390</output>

<result>390</result>