Let her average speed by r mph. After 3 hours, since d=rt, she was r∙3 or 3r miles down the road when Sam left. So the distance between them when Sam left was 3r. His catch-up rate was 43 mph to catch up the 3r distance between them, so since d=rt, 3r = 43∙2 3r = 86 r = 86/3 = 28 2/3 mph Edwin