What is the specific method called on #3

Officer brimberry wrote 24 tickets for traffic violations last week, but only 9 tickets this week. what is the percent decrease? give your answer to the nearest tenth of a percent.

Erin bought christmas cards for $2 each to send to her family and friends. which variable is the dependent variable?

Which equation can be used to measure the density of water in a spherical water tank? let w represent the number of water particles within the region.