Pls help urgently extra points and mark brainlist

Three times the sum of a number and seven is negative thirty-six. what is the number?

Alogical argument that is presented in graphical form using boxes and arrows is called?

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?