Dear Sadeel, 
I think that this sentence has typing errors in it.
 
I believe that the sentence is intended to be:
 
"(The) relation of truancy to other delingency".
 
"Truancy" is when a child stays away from school without permission.  "Delinquency" is minor crime, especially that committed by young people.
 
So, the investigation is: "What is the relationship between truancy and juvenile (young people �s) delinquency?"  "To what extent do truancy and delinquency affect one another?"  "In what way are �staying off school� and �crime or bad behaviour committed by young people� connected?"
 
I hope that this helps you.
 
Les