A problem and its solution

Q. A weather balloon is floating at a constant height above earth when it releases a pack of instruments.

a. if the pack hits the ground with a velocity of -73.5 m/s, how far did the pack fall?

b. how long did it take for the pack to fall?
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v = -73.5 m/s (- since downwards)
a = -g = -9.8 m/s 2
From the equation of motion
v = u + at
-73.5 = -9.8 x t

t=7.5 s

from the equation of motion s = ut + 1/2 a t2
u= 0 m/s
s = 0.5 x (-9.8)x 7.5 x 7.5
= 275.625 m
= 275.6 m