Answer: 300 people can ride in 2 hours. The rate is 150 people per hour. 
 
Step-by-step explanation: You could first find out how many people can ride in an hr by multiplication. We know 50 people can ride in 20 minutes. 
 
 
 
So, 50 x 3 = 150 people can ride in 1 hr (because there are 3, 20-minute increments in 1 hr) 
 
150 x 2 = 300 
 
 
 
300 people can ride in 2 hours. The rate is 150 people per hour.