In school mathematics, functions usually have numerical inputs and outputs and are often defined by an algebraic expression

In school mathematics, functions usually have numerical inputs and outputs and are often defined by an algebraic expression. For example, the time in hours it takes for a car to drive 100 miles is a function of the car’s speed in miles per hour, ?; the rule ?(?) = 100/? expresses this relationship algebraically and defines a function whose name is ?.