Identify your variables and then list what you know about them:
car's speed: 60 mph
time initially traveled by car: 2 hours
distance the car has traveled west after 2 hours: (60 mph)(2 hr) = 120 mi
truck's speed: 55 mph
distance traveled by truck in h hours: (55 mph)h
distance traveled by car = initial 120 miles plus (60 mph)h
total distance traveled by both vehicles:
(55 mph)h + 120 miles + (60 mph)h = 407.5 miles
Solve this equation for the time, h, and then add 2 hours to your result:
(55 mph + 60 mph)h + 120 mi = 407.5 mi
(115 mph)h = 287.5 mi. Solve this for h. Remember that when h was 0, the car had already been traveling 2 hours. Thus, add 2 hours to h to obtain your final answer: "how many hours does the car travel?"