-- The total distance between the towns = 460 km.
-- For the first 3 hours, he travels at an average speed of 60 km/hr. During that time, he covers (60 km/hr) x (3 hrs) = 180 km.
-- At that point, he still has (460km - 180km) = 280 km to go.
-- If he drives that 280km at an average speed of 70 km/hr, it'll take him (280km)/(70km/hr) = 4 hrs to cover it.
-- His total time for the whole trip is (3 hours for the first part) + (4 hours for the last part) = 7 hours.
