Plane A is descending toward the local airport at a rate of 2,500 feet/minute. It is currently at an altitude of 12,000 feet. Plane B is ascending from the same airport at a rate of 4,000 feet/minute. It is currently at an altitude of 1,000 feet. This system of equations models this real-world situation, where x represents the time in minutes and y represents the altitude in thousands of feet: y = 12 − 2.5x y = 1 + 4x Graph the lines of the two equations, and mark the point of intersection for the two lines. In approximately how many minutes will the two planes be at the same altitude? At what altitude will they be?