Answer
$\displaystyle \sum_{k=1}^{6}\left[7\left(\frac{k}{6}\right)+5\right]$
Work Step by Step
There are n terms in the sum (we don't know n yet)
Each term has the same form:
$[7(\displaystyle \frac{k}{6})+5]$, with the 7, 6 and 5 appearing in all the terms,
the numerator k varies from 1,2,3,...,6.
So n=6 terms, and we use k for indexing:
$\displaystyle \sum_{k=1}^{6}\left[7\left(\frac{k}{6}\right)+5\right]$
