You are hanging 3 display shelves with the same width on a wall so that there is 18 inches of space above each shelf for placing items. each shelf is 3 inches wide. you want the space from the ceiling to the top 18 inches of space and the space below the bottom shelf to a chair rail to be the same. determine the distance from the ceiling to the bottom of each of the shelves so that you can install them. explain how you got your answer.