The question asks for NUMBER of total orders possible. {x, a1, a2, ... an, y} where there element at position i ≤ element at position i+1, is one such TOSET. Similarly, we can have {x, a2, a1, a3, ... an, y} which is another TOSET with the same relation. Both of these TOSET contains the given POSET in question. In this way we can permute a1..an in any order and each permutation will be a new TOSET and will contain the given POSET.