Let Zn = {[a]n | a Z}. If the modulus n is given or irrelevant, we write just [a] for [a]n. Find (with proof) the cardinality of Zn Suppose a Z and n E N. Prove or disprove that [a] [a]n, where [a] is the equivalence class given by [a]n[aln... [a]n. If b is the b times residue of b mod n, prove or disprove that [a'] = [a]. -