-10(d+5)=50 plz help me guys

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?

How many square centimeters of wrapping paper will be used to wrap the shoe box?

Josie buys a pair of boots that retail for $52.00 dollars, however they are currently on sale for 25% off how much does josie pay for the boots if there is also a 6% sales tax on them