Car A leaves the airport at 9:00 am and travels at a constant rate of 30 km per hour. Car B leaves the airport at 9:30 am and travels in the same direction along the same highway at a constant rate of 40 km per hour. At what time will Car B be 40 km ahead of Car A?  Choices:
A) 3:00 pm B) 3:30 pm C) 4:00 pm D) 4:30 pm E) 5:00 pm
At 9:30 am, Car A will be 15 km ahead of Car B.   Car B travels at a rate 10 km per hour faster than Car A.   Car B needs to travel 55 km more than Car A in order to be 40 km ahead.   This will take 55 km/10 km per hour=5.5 hours.   Car B will be 55 km ahead at 3:00 pm.   The answer is 3:00 pm.
<result>A</result>
Car A leaves the airport at 9:00 am and travels at a constant rate of 30 km per hour. Car B leaves the airport at 9:30 am and travels in the same direction along the same highway at a constant rate of 40 km per hour. At what time will Car B be 40 km ahead of Car A?