Hi, Young,
Rephrasing your question:
" A row has eight seats, but we have only 5 people. That would leave three seats empty if we took that row, so there are five people in that row which is not completely filled.
Assumptions: The five people sat in the row with 8 seats and there are no other rows in the venue that have unfilled seats. Those can't be confirmed within the language of the original question, making it a bit ambiguous.
Bob
Robert S.
11/25/20
Young S.
Thanks Mr Bob11/25/20