17. If Anne comes home early, then either Barry makes pasta or Carrie takes everyone out to sushi. (a -> (b V c))
18. Unless Anne comes home early, both Barry will make pasta and Donald will go hungry. ~a -> (b & d)
19. Barry makes pasta only if both Anne comes home early and Carrie doesn't take everyone out to sushi. (b -> (a & ~c))
20. Barry will make pasta if Anne doesn't come home early; but if Anne comes home early, then both Carrie will take everyone out to sushi and Donald won't go hungry. (~a -> b) & (a -> (c & ~d))