Help please Solve у/5 = 7

Ling listed all of the factors of a mystery number: 1,2,4,8,16,32 what is the mystery number?

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?

Which expression is rational? 6. , square root two, square root 14, square root 49