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 the items. Each shelf is 3 inches wide. You want the space
from the ceiling to the top 18 inches of 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. Also the height of the shelf is 71 in.