See your levels Brenna went on vacation and sent postcards to all of her family and friends. She needed 45
postcards, but the store only sold them in packs of 12. She bought 4 packs. How many
postcards did she have left over?

3 postcards

Explanation:
So the question says that Brenna bought 4 packs of 12 postcards, which is the same as 4x12.

4x12=48, so Brenna bought 48 postcards.

It says that she only needed 45, so we can subtract 45 from 48.

48-45=3

Brenna had three postcards left over.

Hope this helped you!

The answer is part a: use