The graph shows the relationship between the numbers of cases of hamburgers and hot dogs ordered by a restaurant owner. Each ordered pair represents an order for a certain month. In the graph, x represents the number of hamburgers and y represents the number of hot dogs.
Which sentence represents the function?
The number of hot dogs is always 5 more than the number of hamburgers.
The number of hot dogs is always twice the number of hamburgers.
The number of hot dogs is always half the number of hamburgers.
The number of hot dogs is always twenty less than the number of hamburgers.