To solve this we can use one of the main four kinematic equations, preferably we want something that we can use directly without solving for other values.
So in this problem we know that:
Inital velocity or Vi = 0 (started from rest)
The acceleration of the object = 7.5
The distance the object travels Δx = 87m
So, our best equation here with what we have would be:
Vf² = Vi² + 2aΔx
Now we now that Vi is 0 so:
Vf² = 2aΔx
We need final velocity so lets take the square root of Vf to isolate it:
Vf = √2aΔx
Now we plug in
Vf = √2(7.5)(87)
Vf = 36.124 m/s or 36.1 m/s