9514 1404 393
Answer:
51
Step-by-step explanation:
Let s represent the number of seats in a row. Then the number of rows is (s-9) and the total number of seats is ...
s(s-9) = 2142
s² -9s +4.5² = 2142 +4.5² . . . . . complete the square
(s -4.5) = √2162.25 . . . . . . . . take the positive square root
s = 4.5 +46.5 = 51 . . . . . . . add 4.5
The number of seats in each row is 51.
