# Working with set theory: subtraction, union, and intersection.

If we define the following two sets:

A = {1, 2, 3, 4, 5}

B = {5, 6, 7, 8, 9}

What are the following:

A - B?

A union B? (The union of A and B)

A intersect B? (The intersect of A and B)

#### Solution Preview

...y element in B that is also found in A is 5.

A union B = {1, 2, 3, 4, 5, 6, 7, 8, 9}

The union combines all ...