The entire triangle itself will have an area of 16, because the side length of the entire triangle is 4, so 4x4=16.
Then, we'll have to find the area of the space that is NOT the stacked squares.
If you look closely there are two half-triangles to accompany each square so we can put them together and if you look even MORE closely, all of the side triangles equal HALF of all of the stacked squares combined.
I hope this gave you a clue, but I am warning you that I am not exactly great at math and let alone geometry.