Answer:
The answer is 5.
Step-by-step explanation:
Total number of people noticed by author = 28
Total number of black haired people = 27
So, total number of non black haired people = 1
Also given that 6 people had whole row of seats to themselves.
Let x be the number of non black haired people who had a whole row to themselves.
Since there is only one person with non black hair and has a whole row to himself because it is mentioned that one person had a row to himself which is non black haired.
Looking at above information we can say that x = 1.
Now we can say that the number of black haired people who had a whole row to themselves = 6-x
or
Hence, the answer is 5.