el cumpleaños Ramiro David comí un octavo de la torta Alejandro 514 arroz y Ramiro 3 céntimos Cuánta torta comieron entre los tres​

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?