Sentence 1: The beach was far from the dock, so they were renting a car. 
 Sentence 3: They drove the rental through the town until they got to a steep road 
 Sentence 4:  The small car would not go up the hill so they backed down 
 Sentence 5:  They returned the car to the agency and took the cab to the beach 
 Given Sentence 2: The cab took them to the car rental agency.