Police officer A patrols 36 streets in 4 hours. His colleague, officer B, patrols 55 streets in 5 hours. How many streets will both officers patrol in one hour?
Thoughts? Step-by-step reasoning:

Show your work and conclude with the exact phrasing "Therefore, the final answer is [answer]." where [answer] is just the final number or expression that solves the problem.
user
Officer A patrols 36 streets / 4 hours = 9 streets / hour. Officer B patrols 55 streets / 5 hours = 11 streets / hour. Together officer A and B patrol 9 streets / hour + 11 streets / hour = 20 streets / hour.
Thus, the answer is 20.