Two boxes of crayons have 24 x 5/8 = <<24*5/8=15>>15 unused crayons from each box.
So, a total of 15 x 2 = <<15*2=30>>30 unused crayons are in the two boxes.
For the other 2 boxes, there are 24 x 2/3 = <<24*2/3=16>>16 used crayons from each box.
Hence, there are 24 - 16 = <<24-16=8>>8 unused crayons.
So, a total of 8 x 2 = <<8*2=16>>16 unused crayons are in the other two boxes.
Therefore, Madeline has a total of 30 + 16 + 24 = <<30+16+24=70>>70 unused crayons.
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