Linear functions are used to model situations that show a constant rate of change between 2 variables. For example, the relation between feet and inches is always 12 inches per foot. A linear function of this would be y = 12x where y is the number of inches and x is the number of feet. y = 24x models the number of hours in any given number of days {x}. A possible business application may be as follows: If a cell phone company charges a start-up fee of $50 and then $0.05 for every minute used, the function is y = 0.05 x + 50. Use the library or Internet to find another example of a function. Explain how it works with a three sets of inputs for your example. What is the output of your data? What is the practical use of your function?