Please help asap plz

I'm terrible at math any here is appreciated.

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?

M.xyz =radians. covert this radian measure to its equivalent measure in degrees.