Ella bought some key chains and spent a total of 24$. each key chain cost the same whole-dollar amount. she bought between 7 and 11 key chains. how many keys did ella buy

Three students, javier, sam, and corrine, participated in a fundraiser where people donated a certain amount of money per lap that the student ran. each student also had some initial donations that were collected before the run. the equations that represent each student's total donation, y, based on the number of laps ran, x, is shown below. match each equation with the correct rate of change for that student.