Final answer:
The distance between the two cities is 420 miles, calculated using the formula distance = speed x time with a speed of 120 mph and a time of 3.5 hours.
Step-by-step explanation:
The student is asking how many miles lie between two cities, given that a train took 3.5 hours to travel the distance between them at a speed of 120 mph.
To calculate the distance, you can use the formula: distance = speed × time. Multiplying the speed of the train by the total time it took will give the distance between the two cities.
Distance = 120 mph × 3.5 hours = 420 miles.
Therefore, the distance between the two cities is 420 miles.