When Mr. Curtis drives from Balston to Corning his average rate of speed is 50 mph. When Mr. Donnelly drives from Balston to Corning his average rate of speed is 40 mph. One day they both left Balston at the same time and when Mr. Curtis arrived in Corning, Mr. Donnelly was still two hours away from Corning. The distance from Balston to Corning is _____ miles