1) 3x + 2 = 14x - 75; 2) 2x - 1 = 3x + 99; 3) -x + 11 - 4x = -x + 10x + 11; 4) 3x - 12 - x = -x + 2x - 12; 5) 5x - 0,23x + 17 = -17 - 0,23x; 6) 0,77x - 2x + 13 = -13 + 0,77x.

Решение:

1. \( 3x + 2 = 14x - 75 \)
   \( 2 + 75 = 14x - 3x \)
   \( 77 = 11x \)
   \( x = \frac{77}{11} = 7 \)
2. \( 2x - 1 = 3x + 99 \)
   \( -1 - 99 = 3x - 2x \)
   \( -100 = x \)
3. \( -x + 11 - 4x = -x + 10x + 11 \)
   \( -5x + 11 = 9x + 11 \)
   \( -5x = 9x \)
   \( -14x = 0 \)
   \( x = 0 \)
4. \( 3x - 12 - x = -x + 2x - 12 \)
   \( 2x - 12 = x - 12 \)
   \( 2x - x = -12 + 12 \)
   \( x = 0 \)
5. \( 5x - 0.23x + 17 = -17 - 0.23x \)
   \( 5x + 17 = -17 \)
   \( 5x = -17 - 17 \)
   \( 5x = -34 \)
   \( x = \frac{-34}{5} = -6.8 \)
6. \( 0.77x - 2x + 13 = -13 + 0.77x \)
   \( -1.23x + 13 = -13 + 0.77x \)
   \( 13 + 13 = 0.77x + 1.23x \)
   \( 26 = 2x \)
   \( x = \frac{26}{2} = 13 \)

Ответ: 1) x = 7; 2) x = -100; 3) x = 0; 4) x = 0; 5) x = -6.8; 6) x = 13.