Answer:
The proportion is

Explanation:
We have to:
In June 20 of 500 wagons failed
On July 25 of 625 wagons failed
If we call x the number of wagons and and the number of wagons that had failures then we have to for June:

For July we have

The proportions are the same for both months

The proportion is

This means that of every 25 wagons, one has faults