Anyone know how to answer/attempt this question?
There are $n \geq 2 $ sets each containing 10 elements each. Any 2 sets contain 1 element in common and each 2 elements are only in the same set once.
Prove all elements occur in the same number of distinct sets.
To clarify, "each 2 elements are only in the same set once" means that if we pick any two elements, they will only be found together in the same set once, although each element separately could occur in multiple sets.
