Basically, it is (R being rows) (S being seats)
R times the amount of rows plus 12 is the amount of seats in each row
RAmnt + 12
You know there are 1564 seats
You don’t know the amount of rows
You know the amount of seats in the row minus 12 is the amount of rows in all
seat per row - 12 = rows
To make it easier start making up the number of rows that are possible
Just do x - 12x over and over with the different numbers
X= 1564/y
For example
If y is 5
312.8 - 12y which would be 252.8
