Paul’s birthday cake has 16 candles. he cuts the cake and to eat equal slice in each slice has the same number of candles. how many candles does each slice have?

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?