<PRE><B>Question 1035378</B>
.
At 9am two cars started from the same town and traveled north on the same road. one car averaged 45 miles per hour, 
and the other car averaged 40 miles per hour. In how many hours were the cars 30 miles apart?
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{{{30/(45-40)}}} = {{{30/5}}} = 6 hours is your answer.


45 - 30 = 5 mph is their relative speed. 


It is the rate of increasing the distance between two cars.


Each hour the distance between two cars increases in 5 mph.


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