Two submarines are on a secret mission and need to arrive at a location in the middle of the Atlantic Ocean at the same time. They start out at the same time from positions equally distant from the redezvous point. They travel at different velocities but both go in a straight line. The first submarine travels at an average velocity of 20 km/hr for the first 500 km, 40 km/hr fro the next 500 km, 30 km/hr for the next 500 hm and 50 km/hr for the final 500 km. The second submarine is required to travel at a constant velocity, so the captain needs to determine the magnitude of that velocity. Draw a picture of the problem.