A meeting has to be conducted with 4 managers. Find the number of ways in which the managers may be selected from among 7 managers, if there are 2 managers who refuse to attend the meeting together.	Answers:
A) 18
B) 21
C) 25
D) 30
E) 35

Rationale: the total number of ways to choose 4 managers is 7 c 4 = 35 we need to subtract the number of groups which include the two managers , which is 5 c 2 = 10 . 35 - 10 = 25 the answer is c .
Answer: C