You 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?
that would be the set of all the pens:
{red,blue,green,yellow,red,black}
There are 2 red pens in the set of all the pens, but if you just want a set that contains all the unique colors, then red will occur only once.
To find the set that represents all the pens, we need to combine the pens from both boxes. Let's list down all the pens from each box:
First box: red pen, blue pen, green pen
Second box: yellow pen, red pen, black pen
To represent all the pens combined, we should list down each pen without repetition. The set that represents all the pens would be:
{red pen, blue pen, green pen, yellow pen, black pen}
This set includes all pens from both boxes, without any duplicates.