Speed of the faster car . . . S kph
Speed of the slower car . . . S - 14 kph
Sum of the speeds of the cars = (S) + (S - 14) = 2S - 14 kph
The cars are driving toward each other, so the space between them
is shrinking at the rate of (2S - 14) kph.
Distance = (speed) x (time)
680 km = (2S-14 kph) x (4 hrs)
= 8S - 56 km
Add 56
to each side: 736 km = 8S km
Divide each
side by 8 hrs: S = 92 kph