(a)

Consider the function

The function that models the consumption of Ritalin over the year 1990-1996.

Where is the number of years afterand is measured in grams per 100,000 people.

The equation by replacing by

Interchange x and y in the new equation

Solving this new equation for

Replacing with then the inverse function is ,

Consider the function

The function gives the models the consumption of Ritalin over the year 1990-1996.

Therefore the function represents the year when Ritalin consumption is at a given level .