PLZZZ HELPPP IM FAILLING THIS CLASS

Which expression is equivalent to 3^3 + 2^2?

If the ratio of sum of the first m and n terms of an ap is m2 : n2 , show that the ratio of its mth and nth terms is (2m − 1) : (2n − 1).

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.