Common Sums in a Hexagon 

    A - B - C
   / \     / \
  D   E   F   G
 /     \ /     \
H - I - J - K - L
 \     / \     /
  M   N   O   P
   \ /     \ /
    Q - R - S
Place the numbers 1-19 in the hexagon, such that each of the 12 lines of three numbers have the same sum. What are the lowest and highest possible common sums? (Or is this possible?)
(To aid in solution comparisons, place the lowest valued corner in the top-left position, and the lowest adjacent side in the top-center position.)

Source: Original. Based on a puzzle from Sudipta Das.

Solution
Mail to Ken