Answer:
22.5m/s, this is assuming conservation of energy and that the girl starts coasting from rest
Explanation:
conservation of energy: mgh = 1/2 m*v^2
h = 25.8m, m = 64.6kg, g=9.81m/s^2
plug in and solve for v
v = sqrt(2gh) = sqrt(2*9.81*25.8) = 22.5m/s