I would very much like some help to the following problem. 1. The problem statement, all variables and given/known data Using mathematical induction, prove that a finite set A of n elements has n(n-1)/2 subsets of two elements. 3. The attempt at a solution * Base step n=2: 2(2-1)/2= 1 subset of two elements. * Inductive step: assuming the statement holds for n=k, that is a set A of k elements has k(k-1)/2 (hypothesis) We want to show that it also holds for n=k+1, that is a set A of k+1 has (k+1)(k+1-1)/2 elements. How can we infer from the hypothesis ??? I have no idea ... I have an engineering background so be as descriptive as you can. Thank you in advance.