(WX + Z’)(Y’ + Z) + W’(X+Y’)

I used the association property on the first operand and it leads me nowhere further from this initial expression.

This is what I did:

(WX + Z’)(Y’ + Z) + W’(X+Y’)

WXY' + WXZ + Z'Y' + Z'Z + W'(X+Y')

WXY' + WXZ + Z'Y' + W'(X+Y')

and now I can't seem to figure out what to do next. Any help is much aprecciated!