During the current year, Central Auto Rentals purchased $60$ new automobiles at a cost of $$14,000$ per car. The cars will be sold to a wholesaler at an estimated $$7,000$ each as soon as they have been driven $50,000$ miles. Central Auto Rentals computes depreciation expense on its automobiles by the units$-$of$-$output method, based on mileage.

a$.$ Compute the amount of depreciation to be recognized for each mile that a rental automobile is driven.

b$.$ Assuming that the $60$ rental cars are driven a total of $1,710,000$ miles during the current year, compute the total amount of depreciation expense that Central Auto Rentals will recognize on this fleet of cars for the year.