I need help solving this

Compare the cost of the bike trips from the two companies shown.for both the cost in a linear function of the number of days which statements is true

Find the solution of this system of equation -7x+y=-20 9x-3y=36

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?