5. Решите уравнения: 1) x + 36 = 22 + 71 2) x - 45 = 31 - 28 3) (x - 18) + 15 = 21 4) (x + 12) - 6 = 42

Решение:

1. \( x + 36 = 22 + 71 \)
   \( x + 36 = 93 \)
   \( x = 93 - 36 \)
   \( x = 57 \)
2. \( x - 45 = 31 - 28 \)
   \( x - 45 = 3 \)
   \( x = 3 + 45 \)
   \( x = 48 \)
3. \( (x - 18) + 15 = 21 \)
   \( x - 18 + 15 = 21 \)
   \( x - 3 = 21 \)
   \( x = 21 + 3 \)
   \( x = 24 \)
4. \( (x + 12) - 6 = 42 \)
   \( x + 12 - 6 = 42 \)
   \( x + 6 = 42 \)
   \( x = 42 - 6 \)
   \( x = 36 \)

Ответ: 57; 48; 24; 36.