## College Algebra 7th Edition

We have a sequence with: $a_1=25$ $a_2=24$ $a_3=23$ $a_n=26-n$ So: $a_{12}=26-12=14$ To find the sum, we use: $S_n=\frac{n}{2}(a_1+a_n)$ $S_{12}=\frac{12}{2}(a_1+a_{12})$ $S_{12}=6(25+14)=39*6=234$