Respuesta :
You can use the arithmetic sequence equation. This will tell you the number of seats in the last row
An = A1+ (n-1)d
An = 4+(24-1)5
An = 4 + (23)(5)
An = 4 + 115
An = 119
Then, you take that answer and plug it to this equation: Sn = n(a1 + an)/2
Sn = 24(4+119)/2
Sn = 24(123) /2
Sn = 1476
An = A1+ (n-1)d
An = 4+(24-1)5
An = 4 + (23)(5)
An = 4 + 115
An = 119
Then, you take that answer and plug it to this equation: Sn = n(a1 + an)/2
Sn = 24(4+119)/2
Sn = 24(123) /2
Sn = 1476