300
If you fill a glass with water and ice cubes, mark the water line with a pen and wait for the ice cubes to melt where is the water line?
What is sitting at the line you marked ?(Archimedes principle: an object floating in water will displace enough water to match its weight. Ice weighs the same melted as frozen, so the water displaced by the ice cube gets exactly filled in when it melts and the water level does not change.)