So I started with xy'+x'y+xz+y'z
I used a Kmap and ended up with the equvalent solution
z+x'y+xy'
From here I need to make this into a sum of two products and take the complement of it to get the solution I need.
But I see no way to turn this into a sum of two products
I can use the distributive law and end up with (z+x')(z+y)+xy'
But I'm pretty sure this is not sum of two products, at least not in the sense my book was showing me