This problem can be solved through simple arithmetic progression
Let
a1 = the first term of the sequence
a(n) = the nth term of the sequence
n = number of terms
d = common difference
Sn = sum of all terms
given
a1 = 12
a2 = 16
n = 10
d = 16 -12 = 4
@n = 10
a(n) = a1 + (n-1)d
a(10) = 12 + (9)4
a(10) = 48 seats
Sn = (n/2) * (a1 + a(10))
Sn = 5* (12 + 48)
Sn = 300 seats
Therefore the total number of seats is 300.