A red car and a green car move toward each other in adjacent lanes and parallel to an x axis. At time t = 0, the red car is at xr = 0 and the green car is at xg = 216 m. If the red car has a constant velocity of 21.0 km/h, the cars pass each other at x = 44.6 m. On the other hand, if the red car has a constant velocity of 42.0 km/h, they pass each other at x = 76.0 m. What are (a) the initial velocity (in km/h)