GMATinsight wrote:

If 3 members are to be selected from a group of x members then what is the value of x?

1) If team of 3 members is selected from the group of x members then 30 different combinations of 3 members can be formed with 2 specific members never being together on the team

2) There are a total of 35 ways to make team of 3 members out of team of x members.

Source:

http://www.GMATinsight.com we have to find x.

From1 : 2 specific members never being together=Total number of combinations- 2 specific members being together.

Total number of combinations=xC3

2 specific members being together=(x-1)C3

xC3-(x-1)C3=30

Since one equation one variable . So 1 is sufficient.

From2 : xC3=35

Again one equation one variable . So 2 is also sufficient.

No need to find value it will take your time.

So D.