Let . Write down the cosets of the subgroup of generated by ; by ; by ; by . Verify Lagrange's theorm for each case.

Previously was the group (under multiplication) of units of

What are the subgroups and how do I find the cosets of those subgroups?

I really only need help getting started with one then I'm sure I'll be able to do the rest, I'm just not certain what the question is looking for.