On a scale drawing with a scale of 1/20, the height of the building is 8 inches. how tall is the actual building in feet?

That means its downgraded to 1/20 of actual height, let actual height is x. Then 
(1/20) * x = 8, x = 20 * 8 = 160, actual height = 160 inch
160 inch = 160/12 feet = 13 1/3 feet or 13.333 feet.

We’re gonna need a picture to refer to in order to figure it out. try reposting your question with the picture included.