Passing on a Track

Two cars (A and B) start at the starting line at the same time on a 3-mile long track, going in opposite directions.  As they drive around the course, they pass each other many times.  Exactly one hour after starting, they pass each other for the 33rd time.  At this point car A has completed exactly 20 laps.  What is the average speed of Car B?

Source: Original, based on a puzzle from Emanuel Manasci

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