Mary ran 3/8 x 24 = <<3/8*24=9>>9 kilometers.
Edna ran 2/3 x 9 = <<2/3*9=6>>6 kilometers.
Lucy ran 5/6 x 6 = <<5/6*6=5>>5 kilometers.
Lucy should run 9 - 5 = <<9-5=4>>4 kilometers more.
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