Explicação passo-a-passo:

[tex]a)15 + x = 2x + 9 \\ x - 2x = 9 - 15 \\ x = - 6[/tex]

[tex]b)17x - 7x = x + 8 \\ 17x - 7x - x = x + 8[/tex]

[tex]9x = 8 \\ x = \frac{8}{9} [/tex]

[tex]c)x + x - 4 = 17 - 2x + 1 \\ 2x + 2x = 18 + 4 \\ 4x = 22 \\ x = \frac{22}{4} = \frac{11}{2} [/tex]

[tex]d)x + 2x + 3 - 5x = 4x - 9 \\ - 2x - 4x = 9 - 3 \\ - 6x = - 3 \: \: \: \times ( - 1) \\ 6x = 3 \\ x = \frac{3}{6} = \frac{1}{2} [/tex]

[tex]e)5x + 6x - 16 = 3x + 2x - 4[/tex]

[tex]5x + 6x - 3x - 2x = - 4 + 16 \\ 6x = 10 \\ x = \frac{10}{16} = \frac{5}{8} [/tex]

[tex]f)5x + 4 = 3x - 2x + 4[/tex]

[tex]5x - 3x + 2x = 4 - 4 \\ 5x = 0 \\ x = \frac{0}{5} = 0[/tex]