In the given question it is important to take note of every minute details that are given in the question. using these details the answer to the given question can be easily reached.
Let us assume the common ratio to be x.
Then
x + 9x = 81
10x = 81
x = 81/10
= 8.1
A s we already know that the ratio of chaperones to students is 1:9
Then
The number of chaperones = 1 * 8.1
= 8.1
So 8.1 chaperones were there in total. I hope you have got the answer you were looking for.