At least a third of Fred's marbles are dark blue. All of the rest are red, except for 4 that are green. If he has 63 marbles, how many of them are red?
Fred has 63/3 = <<63/3=21>>21 dark blue marbles.
Fred has 63-21 = <<63-21=42>>42 red and green marbles.
Fred has 42-4 = <<42-4=38>>38 red marbles.
#### 38