I will have to make some assumptions here, in the absence of information from you. One such thing is the number of elements in this series; it seems to be 28. If that is correct, then you want to sum up the first 28 elements of this series.
28 28 28(28+1)
First focus on ∑ (9k) = 9[ ∑ k ] = 9 * ------------- = (9/2)(28^2+28) = 3654
n=1 n=1 2
Then focus on the 2nd term:
28
∑ 4 = 4∑1 =4(28) = 112
n=1
Then add together 3654 and 112 to obtain the sum of the first 28 terms of this series 9k-4. It is 3766.
