Find the surface area of the solid. LABEL pls help me with both of the problems!

Ineed solving this problem h/8=-25 solve for h idk how to this can someone show me and also give an answer you

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?

If the tip varies directly with the number of guest which equation represents between the tip, t, and the number of guest, g?