For notation, let + be OR and x be AND
Whilst your final expression is correct, it is not simplified. You should use the distributive law to simplify and de Morgan's law on .
From there, a tip would be to label the value you see twice to some value, say D.
You end up with , which is equal to (and of course substitute back in D)
My boolean algebra is a bit rusty, so if I make a mistake please point it out.