The average monthly salary of 8 workers and one supervisor in a factory was $$430. When the supervisor, whose salary was $$870 per month, retired, a new person was appointed and then the average salary of 9 people was $$400 per month. The salary of the new supervisor is:	Choose the correct answer.
A) 233 B) 600 C) 287 D) 771 E) 191
Explanation:   Total salary of 8 workers and supervisor together = 9 × 430 = 3870   Now total salary of 8 workers = 3870 − 870 = 3000   Total salary of 9 workers including the new supervisor = 9 × 400 = 3600   Salary of the new supervisor = 3600 − 3000 = 600   Answer: 600
<result>B</result>
The average monthly salary of 8 workers and one supervisor in a factory was $$430. When the supervisor, whose salary was $$870 per month, retired, a new person was appointed and then the average salary of 9 people was $$400 per month. The salary of the new supervisor is: