You have a ball (volume V, average density B) and a glass beaker. The ball is attached to the bottom of the beaker with a light spring (coefficient k). When you fill the beaker with a liquid of density L, the ball floats fully submerged under the surface with the spring extended by x.

Derive the expression for xx in terms of V, B, L, and k. Express your answer in terms of some or all of the variable's V, B, L, and k. Use g for the free-fall acceleration.