Set this up as ratio with feet on top and minutes on the bottom: . Cross multiply to get 213x = 112 and solve for x to get x = .52 feet. This means that after she has been descending for 8 minutes she is a half a foot from the top.
Change the inches into feet. There are 12 inches in a foot so divide 144 by 12. That gives you 12, so then multiply 12 by 14. You are left with 168 feet.