the format of your question screams "copy and paste" from your homework;
That's a little frowned upon here, so lets do it right:
can you show us the query you've created so far, and explain what doesn't work, or where you are stuck?
we would love to help you master the problem, rather than do it for you;
you'll suffer later if you don't grasp this concept yourself, because later homework will certain build on top of the basics like this.
Lowell