The chorus has 30 members. what expression represents the number of ways a group of 6 members can be chosen to do a special performance?

The problem uses the concept of Combination where there are number of members chosen from a group and there order is not important. Thus, the expression that would best describe the given above is 30C6 which means the combination of 30 taken 6. The numerical value for this is 593775. 

Just tell koda to adjust the number of shapes himself.