Answer:
I suppose that this question is about ratios.
When we have A elements of one type, for every B elements of another type.
The ratio between these elements is A:B
In this particular case, we have:
5 beetles out of 45 insects (the 5 beetles do not belong to the group of 45 insects, if that where the case, we would not get the value 1:9 seen in the question)
Then there are 5 beetles and 45 insects.
The ratio is 5:45
Now, whit those we can divide both numbers by the same number and the ratio will be the same, then if we divide both by 5, we get:
(5/5):(45/5)
1:9