Question 342043
In 2 hours, the 1st car is 80 miles away (40*2).
The 2nd car gains on the 1st at 20 mph (60 - 40).  Or, the speed of the 2nd car relative to the first is 20 mph.
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80/20 = 4 hours to overtake.
2 PM + 4 hours = 6 PM