UP Police SI Exam 12 Dec 2017 Shift 2 Solved Paper

The average age of a group of n people increases by 12 if Tarun and Arun are excluded. The total age of two new people, Rohit and Mohit, is the same as that of Tarun and Arun. If Rohit and Mohit are added to the group of n people, the average age decreases by 4. Find n?