We don't know the acceleration so let's use an equation that doesn't involve the acceleration:
x = x0 + (1/2)(v0 + v)t
I'm envisioning a coordinate system where + x is in the direction of motion and the origin is at where the person starts to decelerate. Thus x0 = 0 ft, v0 = 650 ft/min, v = 0 ft/min. Using the unit conversion from my first post we get that
v0 = 10.833333 ft/s.
x = (1/2)(v0)t = (1/2)(10.833333 ft/s)(25 s) = 135.417 ft
So 135 ft.