Answer:
Question relates to a Arithmetic Sequence {30,32,34...} where d = 2
and the terms are the enumber of seats in each row.
S%5Bn%5D=%28n%2F2%29%282%2Aa%5B1%5D%2B+%28n-1%29d%29 |Sum of the seats in the 26 rows.
S%5B26%5D=%2826%2F2%29%282%2A30%2B+%2825%292%29 = 1430 seats in the ALL 26 rows
Explanation: