Verified answer

The sigma notation means summation. You simply substitute the integer values from 2 to 5 into 3n-6 and then add up all of the answers.

start at n = 2

6-6 = 0

n = 3

9-6 = 3

0 + 3 = 3

n= 4

12-6 = 6

3+6 = 9

n=5

15- 6 = 9

9 + 9 = 18