Answer:
Speed in heavy traffic is 32 miles per hour
Explanation:
Total distance = 252miles
Total time = 4.5hours = 4 hours + 30minutes
Let the speed in heavy traffic = x
distance = time * speed
First half hour
D1 = 0.5*x
The speed after the traffic = 2x - 5
D2= 4* (2x - 5)
Total distance = D1 + D2
+ 8x - 20 = 252
= 272
x =

x = 32 miles per hour