Answer:
30.6 feet
Step-by-step explanation:
first she descends 10.7 feet then she goes up 8.6 so you subtract: 10.7 - 8.6 which equals 2.1. So she is currently only down 2.1 feet. Then she descends 28.5 more feet so you add 28.5 + 2.1 which equals 30.6 feet.
