Omar got a train ticket valid for the nine cities listed below. He can choose to visit some, none, or all of these cities. Amsterdam, Brussels, Cologne, Dortmund, Duisburg, Lille, Paris, Rotterdam, Utrecht In how many different ways can Omar choose the cities to visit? (The order of the cities chosen doesn't matter.)

Sample response: if the graph passes the horizontaline test, then the function is one to one. functions that are one to one have inverses that a therefore, the inverse is a hinction compare your response to the sample response above. what did you include in your explanation? a reference to the horizontal-line test d a statement that the function is one-to-one the conclusion that the inverse is a function done