Can y’all help me with this?

Find the third, fifth and seventh term sequence described by each rule a(n)=n+1

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?

What is the equation of a line that passes through points (0, 4) and (-4,-8)?