The correct answer is 48 mph
Explain
First, 32 miles
Average speed 64 mph
T1= time for first 32 miles
distance / speed
32 miles / 64 mph = 0.5 hrs
For remaining distance = 200 miles- 32 miles = 168miles
Let average speed = x
T1 = time for rest of journey = distance / speed
168miles / x mph
Since
Total time journey is 4 hours
T1 + t2 = 4hr
Or
0.5 +168/x = 4
168/x = 4-0.5
168/ x = 3.5
X= 168/ 3.5
X= 48 mph