Prove how Circle O is similar to Circle X

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.

Roy has 4 1/2 pizzas for the soccer team to split after the game. if each member is going to get 1/2 of a pizza, how many players are on the soccer team

Two cities a and b are 1400km apart and lie on the same n-s line. the latitude of city a is 23 degrees. what is the latitude of city b. the radius of the earth is approximately 6400km.