a) x + 3 = 2x - 4; б) 2х - 4 = 7x + 2; в) x +4 = x + 2; г) 2х - 6 = 3х; д) 5x = 6x; e) 2x + 5 - 7x + 2 = 3; ж) 3х - 5 = -2х + 7 + 5х - 12; 3) х - 1 + 3x - 5 = (х - 5) - (х - 3) +…

Let's solve each equation step by step:

a) \( x + 3 = 2x - 4 \)

1. Subtract \( x \) from both sides:
   \( 3 = x - 4 \)
2. Add \( 4 \) to both sides:
   \( 7 = x \)
   Solution: \( x = 7 \)

б) \( 2x - 4 = 7x + 2 \)

1. Subtract \( 2x \) from both sides:
   \( -4 = 5x + 2 \)
2. Subtract \( 2 \) from both sides:
   \( -6 = 5x \)
3. Divide by \( 5 \):
   \( x = -\frac{6}{5} \)
   Solution: \( x = -\frac{6}{5} \)

в) \( x + 4 = x + 2 \)

1. Subtract \( x \) from both sides:
   \( 4 = 2 \)
   This is a contradiction. Solution: No solution (inconsistent equation).

г) \( 2x - 6 = 3x \)

1. Subtract \( 2x \) from both sides:
   \( -6 = x \) Solution: \( x = -6 \)

д) \( 5x = 6x \)

1. Subtract \( 5x \) from both sides:
   \( 0 = x \)
   Solution: \( x = 0 \)

е) \( 2x + 5 - 7x + 2 = 3 \)

1. Combine like terms:
   \( -5x + 7 = 3 \)
2. Subtract \( 7 \) from both sides:
   \( -5x = -4 \)
3. Divide by \( -5 \):
   \( x = \frac{4}{5} \)
   Solution: \( x = \frac{4}{5} \)

ж) \( 3x - 5 = -2x + 7 + 5x - 12 \)

1. Combine like terms on the right side:
   \( 3x - 5 = 3x - 5 \)
2. Subtract \( 3x \) from both sides:
   \( -5 = -5 \)
   This is always true. Solution: Infinite solutions.

3) \( x - 1 + 3x - 5 = (x - 5) - (x - 3) + (x + 1) \)

1. Simplify the left side:
   \( 4x - 6 \)
2. Simplify the right side:
   \( (x - 5) - (x - 3) + (x + 1) = x - 5 - x + 3 + x + 1 = x - 1 \)
3. Set them equal:
   \( 4x - 6 = x - 1 \)
4. Subtract \( x \) from both sides:
   \( 3x - 6 = -1 \)
5. Add \( 6 \) to both sides:
   \( 3x = 5 \)
6. Divide by \( 3 \):
   \( x = \frac{5}{3} \)
   Solution: \( x = \frac{5}{3} \)

These are the solutions for each part of the problem set you've provided.