Question 1191454
A ∪ B (A union B) includes all the elements that are in set A, or in set B, or in both.  We simply combine the elements of both sets, making sure not to list any element twice.

* A = {z, y, x, w, v, u}
* B = {x, w, v, t, s, r}

A ∪ B = {z, y, x, w, v, u, t, s, r}