What multiple of 9 is also a factor of 9?

How many sides does a regular polygon have if each exterior angle measure is 45 degrees explain your answer, i really don't understand this.

Seymour is twice as old as cassandra. if 16 is added to cassandra’s age and 16 is subtracted from seymour’s age, their ages become equal. what are their present ages? show !

If private savings 'v' = 0.75s and total savings 's' equals $4.20 billion, solve for public and private savings.