Fred has 38 red marbles, half as many green ones, and the rest are dark blue. If he has 63 marbles, how many of them are dark blue?
Step-by-step reasoning process below:
6
Fred has 38 / 2 = 19 green marbles.

Fred has 63 - 38 - 19 = 6 dark blue marbles.

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Final answer: 6