A trout was swimming 9 feet below the surface of a lake. It dove down 8 more feet to search for food. What is the position of the trout now relative to the surface? (Here’s another one :/ im dumb UwU)

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?