Many to many summary

This is my app structure
Riders 
Schools
Daily routes
Riders in daily routes (many to many)
Schools in daily routes (many to many)

Every school has multiple riders
Every Daily route has multiple riders thru the many to many
Every Daily route has multiple schools thru the many to many

I need to summarize the amount of riders in my route for each of the schools in my route.

What is the best way to do this?

Thanks

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EOM Develepors
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