9. A cheetah is located 100 yards away from an antelope. The cheetah begins running on a straight path toward the antelope at a constant speed of 30 yards per second. At the same time, the antelope begins running away from the cheetah at a constant speed of 25 yards per second. If both animals continue to run on a straight path at the same speeds, how long will it take for the cheetah to catch up to the antelope?