US Express is an overnight package delivery company based in Atlanta, Georgia. Jet fuel is one of the largest operating costs incurred by the company, and the company wants your assistance in managing this cost. The price of jet fuel varies considerably at different airports around the country. As a result, it seems that it might be wise to $$fill up$$ on jet fuel at airports where it is least expensive. However, the amount of fuel an airliner burns depends, in part, on the weight of the plane$$and excess fuel makes an airplane heavier and, therefore, less fuel$-$efficient. Similarly, more fuel is burned on flights from the east coast to the west coast $($going against the jet stream$)$ than from the west coast to the east coast $($going with the jet stream$).$