You are part of the rescue team in a ship at sea. One of your divers is 250 feet below sea level, and she injured herself. She has only a 7 minute supply of air in her tank, and can only rise towards the surface at a rate of 10 feet per minute. You are sending down a rescue sub. The sub can descend at a rate of 30 feet per minute. At what depth, to the nearest foot, will the two meet?