=+a. Many people regularly commute from the suburbs to downtown Pleasantville. Due to traffic congestion, the trip takes 30 minutes via highway but only 15 minutes via side streets.

b. At the intersection of Main and Broadway are two gas stations. One station charges $3.00 per gallon for regular gas and the other charges $2.85 per gallon. Customers can get service immediately at the first station but must wait ina long line at the second.