6. (a) Assume that a and m are odd positive integers with god(a, m) = 1. Compute q*(15m) mod 2m. (b) If god(m, n) = god(a, m) = god(b, n) =1, show that god(an + bm, mn) = 1. (c) Use above fact to compute Z;, from Z; = {1, 2, 3, 4, 5, 6} and Zio = {1,3,7,9}. [Show how you use the fact for your computation!]