Pls help quick! Would greatly appreciate it.

Apositive number a or the same number a increased by 50% and then decreased by 50% of the result?

Acomputer store bought a program at a cost of $10 and sold it for $13. find the percent markup

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?