Potential energy negative, force & displacement co-linear?

[CivilSigma]

Homework Statement

In the following question, in the solution, why is it that when they calculate the gravitational potential energy at point 2 (impact with spring), it is negative? I know that if both the force and displacement act in the same direction, then the work done should be positive. Why is it not the same thing here?

 

[hawkeye1029]

I think they mean both answers could work when the equation is solved...however one answer would obviously make more sense in this case.

 

[CivilSigma]

Oh sorry about that being un-clear. I mean for $$V_g = mgh_2 = (50)(9.81)(-x \sin 20)$$

why is it negative?