## finding flux through a surface

The question,

1[IMG]file:///Users/acosta0809/Library/Caches/TemporaryItems/moz-screenshot.png[/IMG]Compute the flux of the vector field = 12 + 3 + 4 through the following rectangular region, assuming it is oriented as shown.
1

I am very confused as to how to actually do this... i can find the area thats just l x w and i get sqrt(5) but im trying to find the normal vector i think i need to cross multiply two vectors just from the sides of the rectange but from there im stuck... please help