Akash and Equal Mean

Akash goes to class everyday. His classes are held on the $9^{th}$ floor so he uses a lift. One day $N$ people get on the lift. However, since the lift can carry at most $N-2$ people, $2$ of them need to get off. Given an array $A$ of the weights of the $N$ people, Akash wonders how many ways of removing $2$ people exist such that the [mean](https://en.wikipedia.org/wiki/Arithmetic_mean) of weigh