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