After an object is dropped, the distance it falls is
H = 1/2 G T² .
'H' is the distance it falls.
'G' is the gravity on the planet where the object is dropped.
'T' is the number of seconds it spends falling.
On Earth, 'G' is 9.8 m/s² .
H = (1/2) (9.8) (12.5)²
= (4.9) (156.25)
= 765.6 meters .
Notice that we only needed to know how much time he spent falling.
We didn't need to know how far from the wall of the canyon he landed.
That "82 m" is there just to confuse us.
My favorite part of the whole event is always that little poof of dust
as seen from the top of the cliff.