N3+5n2-9n-45 factored?

Last month, a 770 g box of cereal was sold at a grocery store for $3.10. however, this month, the cereal manufacturer launched the same cereal in a 640 g box, which is being sold at $2.50. what is the percent change in the unit price?

The area of a circle is equal to 1 dm². find the radius of the circle.

What is the value of n in the equation -1/2(2n+4)+6=-9+4(2n+1)