At a construction site, a brick fell and hit the ground at 24m/s

Question

a) from what height did the brick fall?

b) how long was it falling?

for a) i got 29.387m and for b) I got 2.448s

I got a) by using v^2=v0^2 +2a(x-x0)
for b) I used v=v0+at

Did I do this problem correctly?

If we use
(v_f)^2 = (v_0)^2 +2g*d where v_0 = 0, g=9.8m/s^2, and v_f=24m/s we have d=29m.
a) looks correct to me with that formula.
For b) v/g=t so the 2.4s looks right.
So yes, it appears to me you used the correct formulas and you did the calculations correctly too. Nice job.
(Be careful not to overstate the digits.)