Answer:
Both The car A and B have same speed , i,e 40 miles per hours 
Explanation:
Given as :
The distance cover by car A = 20 miles
The Time taken by car A = 
 hours
 hours
So , From Distance = Speed ×Time 
Or, 20 miles = speed × 

∴ Speed = 20 × 2 = 40 mph 
So ,  Speed = 40 miles per hour 
Again , 
The distance cover by car B = 30 miles
The Time taken by car A = 
 hours
 hours
So, From Distance = Speed ×Time 
Or, 30 miles = speed × 

∴ Speed = 
 = 40 mph
 = 40 mph
So ,  Speed = 40 miles per hour 
Hence From the solutions for both car A and B , it is clear that both the car have same speed . Answer