Find the sequence whose nth. term is 4n + 5 also prove that sequence is an AP

What is the value of x in the this question ?

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?

Oliver read for 450 minutes this month his goal was to read for 10% more minutes next month if all of her medicine go how many minutes will you read all during the next two months