Answer:
To find the number of stops where people boarded the bus during Monica's ride, we need to divide the total distance of the ride (20.4 miles) by the distance between each stop (0.85 miles).
Number of stops = Total distance / Distance between stops
Number of stops = 20.4 miles / 0.85 miles
Number of stops ≈ 24
Therefore, people boarded the bus at 24 stops during Monica's ride.