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A car wash has two bays. The express bay finishes a car every 45 seconds. The full-service bay finishes a car every 75 seconds. Both open at 09:00. The full-service bay is shut for 20 minutes from 09:30 while a filter is changed, and reopens immediately afterwards. The express bay runs without interruption.

How many cars have the two bays washed in total by 10:00?