d=Vot+1/2at^2
Vot= 0 since there is no initial velocity in the y direction.
a=gravitational acceleration which is - 32 ft/s^2 in imperial units I believe.
She travels a distance of -2 miles, so
-2 miles= 1/2(-32ft/s^2)t^2
t= square root((- 4 miles)/(-32ft/s^2))
I don't know imperial units, but convert miles to feet then solve for t.
