Simplify $(x'+y)'(x+y)'$ with boolean algebra So I'm doing some homework and trying to simplify $(x'+y)'(x+y)'$. So far these are the steps I've completed, but I'm not 100% sure that they're appropriate.
$(x'+y)'(x+y)' = (x'+y)'(x’y’)$
$(x'+y)'(x’y’) = (x’’+ y’)(x’y’)$
$(x’’+y’)(x’y’) = (x+y’)(x’y’)$
I'm unsure of what to do after this step (or if I've made any actual mistakes)

$(x'+y)'(x+y)'=(x'+y)'(x'y')=(x''y')(x'y')=(xy')(x'y')$
Can you do the last step?
