83% of 20 is what number?

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?

Use composition to determine if (x) or h(x) is the inverse of f(x) for the limited domain x2-1.

What is the difference between the equations of a vertical and a horizontal line?