Stella walks down a flight of stairs to the basement. Then she walks back up the stairs and up another flight of stairs to the second floor of her house. Each flight of stairs represents a change of 12 feet in height. How far is Stella above the ground?

12 ft
Because if you start at ground level aka. 0 than go down 12 ft you would be at -12 than you go back up -12+12=0 than up 12 again 0+12=12 so you would be 12 ft above ground level