Astronomers were trying to find the weight of six planets - Mars, Venus, Pluto, Jupiter, Mercury and Saturn. The number of planets lighter than Mars was equal to the number of planets heavier than Venus. Saturn was heavier than Mars and Mercury was heavier than Pluto. Venus was lighter than Mars. Saturn was not the heaviest planet.
Equal sets have the exact same elements, so they must have the same number of elements. Therefore, equal sets must also be equivalent. No, not all equivalent sets are also equal sets
