Assume that before separation, the weight of the milk bottle's contents (mixed milk and cream) is wmix. How does the combined weight of the milk and cream after separation, wsep, compare to wmix

Wsep = Wmix

Explanation:

When Cream and milk up in a bottle they might appear homogeneous but after the bottle must have settled down for a while i.e kept in a position without shaking the bottle. the contents ( cream and milk ) will be separated. this is because Milk and cream do not mix up just like some other liquids that don't mix-up. Wmix represents the weight of the bottle before separation while Wsep represents the weight after separation. but since both liquids are in the same bottle the weight after separation would remain the same

Wsep = Wmix