Clearly indicate the necessary steps, including appropriate formula substitutions, diagrams, graphs, charts, etc. Utilize the information provided to determine your answer. A correct numerical answer with no work shown will receive only 1 point.

Micah vacationed on a Caribbean island in the summer at a luxury hotel. He spent an entire day on a sightseeing excursion that explored the beautiful scenery of the city. Those who went on the trip boarded a bus which went 15mph through a 30 mile section of the city's countryside. There was a lunch stop at a local eatery before the group continued on a 3 hour tour of the city’s sights at a speed of 10mph. Lastly, the bus left the city and travelled 40 miles back to the hotel. Micah arrived back at the hotel exactly 2 hours after leaving the local eatery. What was the bus’s average rate for the entire trip?