[tex]f(x) = \frac{x - 7}{4} - \frac{2x + 3}{6} [/tex]

1)

[tex]x \: \epsilon \: ( - \propto; \: + \propto)[/tex]

2)

[tex]y = 8 \\ \frac{x - 7}{4} - \frac{2x + 3}{6} = 8 \: \: | \times 12 \\ 3(x - 7) - 2(2x + 3) = 96 \\ 3x - 21 - 4x - 6 = 96 \\ - x = 96 + 27 \\ - x = 123 \\ x = - 123[/tex]