Let d be the number of drunk drivers and s be the number of speeders. We know that d + s = 45 and s = 7d - 3.
Substituting the second equation into the first equation, we get d + 7d - 3 = 45
Combining like terms, we get 8d - 3 = 45
Adding 4 to both sides, we get 8d = 48
Dividing both sides by 8, we get d = 6
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