Solve the equations: 1) x + 394 = 512; 2) 5894 + x = 6282; 3) 2401 + x = 7202; 4) 4206 + x = 5208; 5) x + 1244 = 3245; 6) 9987768 - x = 25609; 7) 4284 - (x - 378) = 100; 8) (66625 - x) + 655 = 10006; 9) (x - 12500) + 26448 = 92225.

Решение:

1. \( x + 394 = 512 \)
   \( x = 512 - 394 \)
   \( x = 118 \)
2. \( 5894 + x = 6282 \)
   \( x = 6282 - 5894 \)
   \( x = 388 \)
3. \( 2401 + x = 7202 \)
   \( x = 7202 - 2401 \)
   \( x = 4801 \)
4. \( 4206 + x = 5208 \)
   \( x = 5208 - 4206 \)
   \( x = 1002 \)
5. \( x + 1244 = 3245 \)
   \( x = 3245 - 1244 \)
   \( x = 2001 \)
6. \( 9987768 - x = 25609 \)
   \( x = 9987768 - 25609 \)
   \( x = 9962159 \)
7. \( 4284 - (x - 378) = 100 \)
   \( 4284 - x + 378 = 100 \)
   \( 4662 - x = 100 \)
   \( x = 4662 - 100 \)
   \( x = 4562 \)
8. \( (66625 - x) + 655 = 10006 \)
   \( 67280 - x = 10006 \)
   \( x = 67280 - 10006 \)
   \( x = 57274 \)
9. \( (x - 12500) + 26448 = 92225 \)
   \( x + 13948 = 92225 \)
   \( x = 92225 - 13948 \)
   \( x = 78277 \)

Ответ: 1) x = 118; 2) x = 388; 3) x = 4801; 4) x = 1002; 5) x = 2001; 6) x = 9962159; 7) x = 4562; 8) x = 57274; 9) x = 78277.