So Velocity = final position - initial position divided by time. We are looking for The final position so let's plug in what we know and go from there.
V = -9 m/s Xf = ? Xi = 5m T = 3s
to solve
-9 m/s = (X - 5m) / 3s
-9 x 3 = X - 5
-27 + 5 = X
Xf = 32 m (distance can't be in negative, so we disregard that)
(Hopefully this is right, I haven't done any physics since last year. But it shouldn't be too far off)