1)

[tex] {x}^{2} - 6x = - 5x + 12 \\ x {}^{2} - x- 12 = 0 \\ [/tex]

[tex]d = 1 - 4 \times 1 \times ( - 12) = 49 \\ d = 7 \\ x1 = \frac{1 + 7}{2} = 4 \\ x2 = \frac{1 - 7}{2} = - 3[/tex]

2)

[tex] {x}^{2} + 7x = 6x + 20 \\ {x}^{2} + x - 20 = 0 \\ d = {1}^{2} - 4 \times 1 \times ( - 20) = 81 \\ d = 9 \\ x1 = \frac{ - 1 + 9}{2} = 4 \\ x2 = \frac{ - 1 - 9}{2} = - 5[/tex]