Answer:
1.98 miles per hour.
Step-by-step explanation:
Let x miles per hour be the average rate on the return trip,
∵ The speed on round trip is 5 miles per hour faster than on return trip,
So, the speed in round trip = (x+5) miles per hour,
Now, distance in one sided trip = 6 miles,
Since,

According to the question,
Time taken in return trip - Time taken in round trip =
hours,





By quadratic formula,




∵ speed can not be negative,
Hence, average rate on the return trip would be 1.98 miles per hour.