Yoko does a weekly exercise program consisting of cardiovascular work and weight training. Each week, she exercises for at least 8 hours. She spends at most 12 hours on weight training. She spends at most 4 hours doing cardiovascular work. Let x denote the time (in hours) that Yoko spends doing cardiovascular work. Let y denote the time (in hours) that she spends on weight training. Shade the region corresponding to all values of and that satisfy these requirements.