Leo had 400/10 = <<400/10=40>>40 packs of marbles.
He gave Manny 1/4 x 40 = <<1/4*40=10>>10 packs of marbles.
And, Neil received 1/8 x 40 = <<1/8*40=5>>5 packs of marbles.
Thus, Leo. gave a total of 10 + 5 = <<10+5=15>>15 packs of marbles.
Therefore, Leo kept 40 - 15 = <<40-15=25>>25 packs of marbles.
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