The economic advisor of a large tire store proposes the demand function D(p) = 1800 / p - 40, where D(p) is the number of tires of one brand and size that can be sold in one day at a price p.

a. Recalling that the demand must be positive, what is the domain of this function?

b. According to the model, how many tires can be sold in a day at a price of $60 per tire?

c. Find the elasticity function on the domain of the demand function.

d. For what prices is the demand elastic? Inelastic?

e. If the price of tires is raised from $60 to $62, what is the approximate percentage decrease in demand (using the elasticity function)?