A rock climber's elevation above sea level changed −82 1/2 feet in 2 1/4 minutes as she descended. so the the climber's average change in elevation per minute was: x = -82 1/2 / 2 1/4x = (-165/2) / (9/4)x = (-165/2) x (4/9)x = -18 feet per minute is his change in elevation
