Step-by-step explanation:
Since the weight hangs motionless from the spring, the weight is not in motion and is balanced from vertical components of force ( the spring force and the mg of the weight) so

where f s is the force of the spring.
Now, we can use Hooke Law

where k is the spring constant and x is the displacement of length the spring is stretched.
We know that mg=fs so

mg=w so

k is 75 and x is 0.333
so


or
25 N or 24.98 N