Answer
First three terms: $8,13,18$
last term: $88$
Sum of the an arithmetic series: $816$
Work Step by Step
First three terms can be found as:$a_1=5+3=8;a_2=10+13=13;a_3=15+3=18$
Last term can be found as: $a_{17}=5(17)+3=88$
Sum of the an arithmetic series can be calculated by using formula $S_n=\dfrac{n}{2}(a_1+a_n)$
Here $n=17$
Thus,
$S_{12}=\dfrac{17}{2}(8+88)=816$
our results are:
First three terms: $8,13,18$
last term: $88$
Sum of the an arithmetic series: $816$
