The seating section in a theater has 29 seats in the first row, 34 seats in the second row, and so on, increasing by 5 seats each row for a total of 15 rows. How many seats are in the thirteenth row?
A) $79$
B) $89$
C) $84$
D) $59$
E) $54$

Question

Quizplus · Accepted Answer

The number of seats in each row forms an arithmetic sequence with the first term $a_1 = 29$ and a common difference $d = 5$. The $n$th term of an arithmetic sequence is given by $a_n = a_1 + (n - 1)d$. For the 13th row, $n = 13$, so $a_{13} = 29 + (13 - 1) \times 5 = 29 + 60 = 89$.

The Seating Section in a Theater Has 29 Seats in the First