Question 1207249
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Answer: <font color=red>70 mph</font>



Explanation


The time gap from 9:00 AM to 1:00 PM is 4 hours. 
Think of it like 9:00 AM to 12:00 PM noon (3 hours) and then 12:00 PM noon to 1:00 PM is an extra hour (3+1 = 4 hours total).
Or think of 1:00 PM as 1300 in military time aka 24 hour time format.
9:00 AM would be 0900.
1300-0900 = 400 ---> 4 hours


The train goes from Kansas City to Denver at 80 mph and travels 4 hours when the train passes the bus. 
The train has traveled 80*4 = 320 miles at this point.
Formula: distance = rate*time


x = speed of the bus in mph


The train has already covered 320 miles of the 600 mile total distance.
That leaves the remaining 600-320 = 280 miles for the bus to cover.
distance = rate*time
280 = x*4
x = 280/4
x = <font color=red>70 mph</font> is the speed of the bus.
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