Half of the book means 500 / 2 = <<500/2=250>>250 pages.
Reading the first half took Jane 250 / 10 = <<250/10=25>>25 days.
Reading the second half of the book took Jane 250 / 5 = <<250/5=50>>50 days.
So in total Jane needed 25 + 50 = <<25+50=75>>75 days to read the whole book.
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