He has enough milk to make 18 milkshakes because 72 / 4 = <<72/4=18>>18
He has enough ice cream to make 16 milkshakes because 192 / 12 = <<192/12=16>>16
He can only make 16 milkshakes because 16 < 18
He will use 64 ounces of milk because 16 x 4 = <<16*4=64>>64
He will have 8 ounces of milk left because 72 - 64 = <<72-64=8>>8
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