If Dean takes 9 hours to finish the marathon, it takes Micah 2/3 * 9 hours = <<9*2/3=6>>6 hours to finish the marathon.
It takes Jake 1/3 * 6 hours = <<1/3*6=2>>2 more hours to finish the marathon than Micah.
Jake takes a total of 6 hours + 2 hours = <<6+2=8>>8 hours to finish the marathon.
Micah, Dean, and Jake take a total of 8 hours + 6 hours + 9 hours = <<8+6+9=23>>23 hours to finish the marathon.
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