Answer:
1/5
Explanation:
We have 40 classes total. 8 of the 40 classes are Year 7 classes.
So we can say that
classes are Year 7 classes.
The problem statement asks for the answer in simplest form, so we reduce our fraction by a factor of 8.

So 1/5 (one fifth) of the classes are the secondary school are Year 7 classes.