Eliminate the fractions by multiplying by least common multiple.
4,9,12 all go into 36 evenly. Multiply entire equation by 36.
36/4 = 9
36/9 = 4
36/12 = 3
New equation looks like:
[tex]9(w-1) +4(w+1) = -3(w+1) \\ \\ 9w -9 +4w +4 = -3w -3 \\ \\ 9w +4w+3w = -3 +9 -4 \\ \\ 16w = 2 \\ \\ w = \frac{2}{16} = \frac{1}{8}[/tex]