HELP WILL MARK BRAINLIEST

Find the power series expantion of f(z)=log(4=3z) at the point z=-1

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?

Will give a: 122 b: 90 c: 48 d: 180