"steve starts with $250 and spends $25 a week. chelsea starts with $30 and saves $30 a week. use 'x' for time and 'y' for savings. complete the equations that represent these situations."

steve: y=
chelsea: y=+30x

Steve: y=250-25x. This is because Steve starts with $250 and for every week, which is your unit of time and is represented by variable x, he spends $25. Chelsea: y=30+30x. Chelsea starts with $30, so the 30x is adding to your constant.