1. Scott drew level again with his friend as they cycled along the road at a steady 12 miles per hour. "That's another blue bus, like the one that overtook us exactly 20 minutes ago," he shouted. "Yes, the next one of the same run," replied Declan, glancing at his watch. "And right on time. There's one every 14 minutes this time of day." What was the average speed of the buses?

Bus speed 50 mph

Bus speed 45 mph

Bus speed 40 mph