Answer: t = 108.5 hours
Explanation:
We can represent the velocity of the cars as vectors.
Velocity of first car = 64 mph due east
Velocity of second car = 60 mph due west.
Since both vectors are in opposite direction, the magnitude resultant vector is the difference between the 2 vectors in the direction of the larger vector.
Hence, resultant speed = 64 - 60 = 4mph
Direction of resultant speed = east.
They are 434 miles apart, that's the total distance traveled.
But speed = distance / time.
4 = 434/t
t = 434/4 = 108.5 hours
t = 108.5 hours