Need help now I have 3 min asap

3382-299=3383- ? fill in the blank?

[15 points]find the least common multiple of the expressions: 1. 3x^2, 6x - 18 2. 5x, 5x(x +2) 3. x^2 - 9, x + 3 4. x^2 - 3x - 10, x + 2 explain if possible

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.