Joseph served 18 customers in 42 minutes. Approximately how many customers would he serve in 2 hours if he continued at this rate?

Okay so if he serves 18 customers in 42 minutes divide 18 by 42 and you get the amount of customers he serves per min which is 0.42857413 then multiply that by 120 since 2 hours add up to 120 minutes and you get 51.43