Question 1001269
You would write n = 1 under the sigma.
You would write n = 11 over the sigma.
Since the terms go up by 1.4, the general term would be
a(n) = 6 + 1.4(n-1) = 1.4n + 4.6
You put this after the sigma.
To find the sum, add the first and last terms and multiply that sum by half the number of terms, or
Sum = (n/2)(a(1)+a(n))
Sum = (11/2)(6 + 20) = 143