The average monthly salary of 20 employees in an organisation is Rs. 1200. If the manager's salary is added, then the average salary increases by Rs. 100. What is the manager's monthly salary ?  Choose the correct choice from the following options
A) 3600
B) 3890
C) 3300
D) 2789
E) 2891

Rationale: "explanation : manager ' s monthly salary rs . ( 1300 * 21 - 1200 * 20 ) = rs . 3300 . answer : c"
Answer: C