If there are n rows
And if each row has m seats.
Then the total number of seats shall be n × m.
Here
Number of rows = (c+8)
And number of seats in each row = (4c-1)
Using the concept
Total number of seats
= (c+8)(4c-1)
FOILing or Distributing we get
= c(4c) + c (-1) + 8(4c) +8 (-1)
= 4c² - c + 32 c -8
Combining like terms
=4c² +31c - 8
The expression for total number of seats = 4c² + 31c -8