4) a) (7x+1) – (6x + 3) = 5; б) (8x + 11) - 13 = 9x – 5;

Решение:

1. 4) а)
   1. \( (7x+1) – (6x + 3) = 5 \)
   2. \( 7x + 1 - 6x - 3 = 5 \)
   3. \( x - 2 = 5 \)
   4. \( x = 5 + 2 \)
   5. \( x = 7 \)
2. 4) б)
   1. \( (8x + 11) - 13 = 9x – 5 \)
   2. \( 8x + 11 - 13 = 9x - 5 \)
   3. \( 8x - 2 = 9x - 5 \)
   4. \( 5 - 2 = 9x - 8x \)
   5. \( 3 = x \)

Ответ: 4) а) \( x = 7 \); 4) б) \( x = 3 \).