Chapter 10 - Section 10.2 - Arithmetic Sequences - Exercise Set - Page 1061: 70

$1430$ Seats

We know that $a_n=a_1+(n-1) d$ Here, we have $a_1=30$ and $d=2$ and $a_{26}=30+2(26-1)=80$ The sum of an arithmetic sequence is given by: $S_n=\dfrac{n}{2}[a_1+a_n]$ $S_{26}=\dfrac{26}{2}[30+80]=1430$ Seats