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? Give me reasons, before answering the question
Fred has 63 / 3 = 21 dark blue marbles. Fred has 63 - 21 = 42 red and green marbles. Fred has 42 - 4 = 38 red marbles. So the final answer is 38.