Friction, Spring Constant, Energy

[euphtone06]

Homework Statement

http://img339.imageshack.us/img339/4518/phys2lh6.gif

Homework Equations

W= -um2gh
m1gh=.5Kh^2-um2gh
.5K(h)^2
Final Eq?:
W=um2g*(2g(m1+um2)/K)

The Attempt at a Solution

.2(4)9.8*(2*9.8(7+.2(4))/9 = 133.1754667
I don't know if I went wrong in manipulating the equation but I suspect that's the issue?

 

[euphtone06]

Sorry to bother you guys again but if I could please get some help tonight it would be much appreciated it must be turned in early tomorrow.