If a spring stores 33.5 j of energy when it's compressed by 0.13 m, what is the spring constant of the spring?

Energy, in terms of work, is expressed in units of Joules. Work is also force times distance. From work, we could then find the value of the force:

W = Fd
33.5 = Force x 0.13 m
F = 257.69 N

Apply Hooke's law then. Hooke's law is expressed as Force = k(delta x). From here we could determine the value of the spring constant:

257.69N = k x 0.13m
k = 1982.23 N/m