(A ) The sequence formed is an arithmetic progression, that is
12, 16, 20, 24, .....
the n th term of an arithmetic progression is
[tex]a_{n}[/tex] = [tex]a_{1}[/tex] + (n - 1 )d
where d is the common difference and [tex]a_{1}[/tex] the first term
d = 16 - 12 = 20 - 16 = 24 - 20 = 4 and [tex]a_{1}[/tex] = 12
[tex]a_{n}[/tex] = 12 + 4(n - 1 ) = 12 + 4n - 4 = 4n + 8 ← explicit rule
(B)
solve 4n + 8 = 60 ( subtract 8 from both sides )
4n = 52 ( divide both sides by 4 )
n = 13 ← row 13 has 60 seats
