Answer:
80 miles per hour
Explanation:
Eric takes a train to his parent’s house 320 miles away.
If the trip takes 4 hours.
A train covers 320 miles in 4 hours.
The unit rate of train is number of miles cover in 1 hour.
Using formula:

where, distance = 320 miles
Time = 4 hours


Hence, The unit rate of train is 80 miles per hour.