## Precalculus (6th Edition) Blitzer

$396$
Formula to calculate the sum of an arithmetic sequence is: $S_n=\dfrac{n}{2}(a_1+a_n)$ ...(1) Here, $a_1:$ First term and $a_n=$last term and $a_1:$ First even term is 22 and $a_n$:last term is 44, thus the total even terms are $12$.Then use equation (1) to get the sum of the sequence. Thus, $S_{12}=\dfrac{12}{2}(22+44)\\=6(66)\\=396$