-3x A 5x B
-4x A B -2x C -8x D
8x E 3x F 4x G
4x A D C B 6x E F G 2x H
-1x I 2x J
-9x I J -4x K -7x L
3x A F D H E G C B 1x I L K J
Sol: A = -5; B = -3; C = -4; D = 5; E = -3; F = 4; G = 3; H = 2; I = -2; J = -1; K = 5; L = 1