RBI Assistant Mains 2017 Sitting 3 Paper

The average scores of P, Q and R in Test-A was 80 marks. In Test-A, P scored 4 marks less than Q. In Test-B, P got 6 marks less and Q got 4 marks more (as compared to their respective scores in Test-A) ; and the sum of P's and Q's scores was 144 marks. What was the difference between P's score and R's score in Test -A ?