Question

ou have two boxes of colored pens. The first box contains a red pen, a blue pen, and green pen. The second box contains a yellow pen, a red pen, and a black pen. What is the set that represents all the pens?

Answer 1

You just have to take the union of these sets.
So all that are in the first set and all that are in the second set. (same thing cannot appear twice as that is just the same)

Answer 2

is this the answer ??? {red pen, blue pen, green pen, yellow pen, black pen}