4Σk=1 (k+9)^2

The expression should be read as (k = 1 through 4, sigma (k+9)^2)

Sigma means that you should add the terms.

How many terms? K ranges from 1 to 4, so there are 4 terms (K=1, k =2, k=3,k=4)

What are the terms? To get the first term, you substitute k = 1 in the given
expression. To get the second term, you substitute k = 2 and so on.

The given expression is (k + 9)^2

1st term = (1 + 9)^2 = 10^2 = 100
2nd term = (2 + 9)^2 = 11^2 = 121
3rd term = (3 + 9)^2 = 12^2 = ... you get the idea.

Find the 4 terms, and just add them to get the answer.

Hope this helps :) Let me know if it's not clear.