Algebra 2 (1st Edition)

$\displaystyle \sum_{n=1}^{7}\frac{n}{n+3}$
There are seven terms (we count through numerators, starting with 1) ( $\displaystyle \sum_{n=1}^{7}a_{n}$ ) in which the numerator of the n-th term is $n,$ and the denominator is $n+3$. So, $a_{n}=\displaystyle \frac{n}{n+3}$ Sum = $\displaystyle \sum_{n=1}^{7}\frac{n}{n+3}$