Can someone help me with
20 please show all work

Answer this question! 30 points and brainliest!

Which of the following represents a number squared is equal to twenty more than nine times that number ? a) x squared = 9x + 20 b) x squared = 20x + 9 c) x squared > 9 + 20x d) x squared = 9 + x + 20

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.