Jane had a 500 page book to read. The first half of the book Jane read with a speed of 10 pages per day, and the second half with a speed of 5 pages a day. How many days did Jane spend reading this book?
Half of the book means 500 / 2 = 
<gadget id="calculator">500/2</gadget>
<output>250</output>
250 pages.
Reading the first half took Jane 250 / 10 = 
<gadget id="calculator">250/10</gadget>
<output>25</output>
25 days.
Reading the second half of the book took Jane 250 / 5 = 
<gadget id="calculator">250/5</gadget>
<output>50</output>
50 days.
So in total Jane needed 25 + 50 = 
<gadget id="calculator">25+50</gadget>
<output>75</output>
75 days to read the whole book.

<result>75</result>