. Rachel has 12 baseballs and 18 basketballs. If she wants to divide them into identical groups without any balls left over, what is the greatest number of groups Rachel can make?

Let u = {q, r, s, t, u, v, w, x, y, z} a = {q, s, u, w, y} b = {q, s, y, z} c = {v, w, x, y, z}. list the elements in the set.a ∩ (b ∪ c)a) {q, s, w, y}b) {q, y, z}c) {q, s, u, w, y, z}d) {q, r, w, y, z}