The tallest of 3 trees is 108 feet.  The middle sized tree is 6 feet less than half the height of the tallest tree. The smallest tree is 1/4 the height of the middle tree.  How tall is the smallest tree?
Tallest Tree: <<108=108>>108 feet
Middle sized tree:(108/2)-6=<<108/2-6=48>>48 feet
Smallest tree:48/4=<<48/4=12>>12 feet
#### 12