1. The problem statement, all variables and given/known data Prove that if H is a subgroup of a finite group G, then the number of right cosets of H in G equals the number of left cosets of H in G 2. Relevant equations Lagrange's theorem: for any finite group G, the order (number of elements) of every subgroup H of G divides the order of G. 3. The attempt at a solution I know how to find subgroups of groups, and how to get the cosets from there. But i just dont understand how to show that right and left cosets will be equal because the group is finite.. Im stuck :( thanks for any help!!