Since Krystal and Scott is heading on opposite
directions, therefore the distance between the two would be the sum of their
distances from where they left, so:
total distance (d) = distance covered by Krystal (dK) +
distance covered by Scott (dS)
d = dK + dS
We know that the formula for distance is:
distance = velocity * time
So,
d = vK * t + vS * t
where
vK = velocity of Krystal = 61 mph
vS = velocity of Scott = 65 mph
d = 252 miles
Therefore:
252 = 61 t + 65 t
126 t = 252
t = 2 hours
Therefore Scott needs to travel for 2 hours.