6) 8 = 3(x-4)-x; г) 3 (x - 1) + x = 2x; e) 5 (x + 4) + x = 6; 3) 3 (x-7)-6x = -x; к) 2 (x + 3/5); M) -2(1/3x + 7) = -21

Решение:

1. 6) \(8 = 3(x-4) - x\)
   \(8 = 3x - 12 - x\)
   \(8 = 2x - 12\)
   \(8 + 12 = 2x\)
   \(20 = 2x\)
   \(x = 10\)
2. г) \(3(x-1) + x = 2x\)
   \(3x - 3 + x = 2x\)
   \(4x - 3 = 2x\)
   \(4x - 2x = 3\)
   \(2x = 3\)
   \(x = \frac{3}{2}\)
3. e) \(5(x+4) + x = 6\)
   \(5x + 20 + x = 6\)
   \(6x = 6 - 20\)
   \(6x = -14\)
   \(x = -\frac{14}{6} = -\frac{7}{3}\)
4. 3) \(3(x-7) - 6x = -x\)
   \(3x - 21 - 6x = -x\)
   \(-3x - 21 = -x\)
   \(-21 = -x + 3x\)
   \(-21 = 2x\)
   \(x = -\frac{21}{2}\)
5. к) \(2(x + \frac{3}{5})\) - это выражение, а не уравнение.
6. M) \(-2(\frac{1}{3}x + 7) = -21\)
   \(-\frac{2}{3}x - 14 = -21\)
   \(-\frac{2}{3}x = -21 + 14\)
   \(-\frac{2}{3}x = -7\)
   \(x = -7 \cdot (-\frac{3}{2})\)
   \(x = \frac{21}{2}\)

Ответ: 6) x = 10; г) x = 3/2; e) x = -7/3; 3) x = -21/2; M) x = 21/2.