Average runs scored by 11 players in a match were 35. Average runs scored by players except Virat and Rohit, was 26. Runs scored by Virat were 53 more than that by Rohit. If Virat scored all the runs by hitting fours (4 runs) and sixes (6 runs) , then find the number of sixes hit by Virat. (Note: Virat played 20 balls only and he either hits six or four on each ball)