Danny has a basement in his house. the elevation of the basement floor is -18.9 feet. a storage cabinet is placed on the basement floor. the top of the storage cabinet has an elevation that is equal to of the approximate elevation of the basement floor. a shelf is placed at a height of 2.5 feet above the storage cabinet. what is the approximate elevation of the shelf? a. -22.7 feet b. -16.7 feet c. -11.7 feet d. -9.7 feet