Call the points A, B, C, D , E, F
Let A= (0,0) B = (3,0) C = (8,0) D = (14,0) E = (21,0) F = (23,0)
Choosing any 2, we have C(6, 2) = 15 possibilities
EF = 2 CD = 6 DF = 9 CF = 15 AE = 21
AB = 3 DE = 7 CE = 13 BE = 18 AF = 23
BC = 5 AC = 8 AD = 14 BF = 20
BD is the "Missing Link" = "n" = 11
However....some members might consider "Ginger Ale" to be the "Missing Link".....I'll have to let them decide that for themselves ........