V was standing in a queue immediately behind P. Four persons were waiting in between P and U.
|  | Case 1 | Case 2 | Case 3 | 
|  | Person | Person | Person | 
| 7 | V | U |  | 
| 6 | P |  | U | 
| 5 |  |  |  | 
| 4 |  |  |  | 
| 3 |  | P |  | 
| 2 |  | V | P | 
| 1 | U |  | V | 
One person was waiting in between R and T. S is waiting in front of T. More than two persons were waiting in between S and V.
Hence, case 2 and case 3 are invalid.
|  | Case 1a | Case 1b | 
|  | Person | Person | 
| 7 | V | V | 
| 6 | P | P | 
| 5 | Q | R/T | 
| 4 | T | Q | 
| 3 | S | R/T | 
| 2 | R | S | 
| 1 | U | U | 
The number of persons who wait in front of Q is one more than the number of persons who wait behind R.
Hence, case 1a is invalid
So, final arrangement is
|  | Case 1b | 
|  | Person | 
| 7 | V | 
| 6 | P | 
| 5 | R | 
| 4 | Q | 
| 3 | T | 
| 2 | S | 
| 1 | U | 
The number of persons waiting between P and T is one less than the number of persons waiting between R and U