COMPUTER TABLETS Last year, an office supply store sold 220 computer
tablets for $420 each. This year its manager is considering reducing the
price to increase sales. She estimates that for each $12 decrease in price,
the store will sell 20 additional tablets.

a. Define variables and write a function to represent the situation.

b. How much should the store charge for each tablet to maximize its profit?

c. Find the domain and range in the context of this situation.