Answer: 18 rows.
Explanation:
The theatre has 4 chairs in a row.
There are 5 rows.
If we consider rows as unit, then we observed that
Length = 4 rows
Width = 5 rows
Perimeter of Rectangle = 2(length +breadth)
= 2(5+4)
= 2(9)
=18 rows
Hence, the perimeter is 18 rows.