Student or Learner
This car is Robert and Nancy`s.
That car over there is ( ) Lucy and mine
( ) mine and Lucy´s
( ) Lucy`s and mine.
Apart from the first one, are any of the other sentences right?
You have it down well.
When you have two or more names who possess a single item, you only put the possessive apostrophe-s on the last name. The car is Robert and Lucy's.
When you have two items, of separate possession, then you use: Those drinks on the bar are Robert's and Lucy's.
When the first person (I / me) is involved, it is always listed last to be polite, so it's The car is Robert's and mine. You noticed the apostrope-s on the first one, otherwise it would come out as The car is Robert and mine's. Gasp!