Answer:
15 mph
Step-by-step explanation:
Speed can be found using the following formula. 
s=d/t 
where d is the distance and t is the time. 
The car traveled 30 miles in 2 hours. Therefore, the distance is 30 miles and the time is 2 hours.
d=30 miles 
t=2 hours 
s= 30 miles/2 hours
Divide 30 by 2
s=15 miles/hour 
The car's speed is 15 miles per hour.