Hi there!
We can use the following derivations of the kinematic equations Δd = vit + 1/2at² and vf² = vi² + 2ad to solve:
A)
t = √2h/g, let g = 9.8 m/s²
Plug in the given values:
t = √2(830)/9.8 ≈ 13.05 sec
B)
Use the equation vf = √2ad:
vf = √2(9.8)(830) ≈ 127.55 m/s