You do not need to pass in the argument (double numberOfCups) to getCups. You should declare numberOfCups as a double within the method.
You could make the method more resilient. What would happen if the user entered a string (e.g. "Hello") or a negative number?
You could pass the question string "Enter number of cups" as a String argument, check that the user enters a sensible value and return the value if it is, otherwise provide some guidance and ask the question again.