a)
[tex]11x - 6 = 7x - 4 \\ 4x = 2 \\ x = \frac{2}{4} = \frac{1}{2} [/tex]
b)
[tex]4x + 3 = 9x - 12 \\ - 5x = - 15 | \div (- 5) \\ x = 3[/tex]
