Answer:
24
Explanation:
starting with the "top floor" :
3 single small triangles.
then the left 2 combined and the right 2 combined.
and then all 3 combined.
that is 3 + 2 + 1 = 6 triangles.
now we extend the triangles from the top floor to the next floor below.
we have the same number of triangles, they are just longer.
6 triangles there.
and we extend the triangles to the next floor below.
we have again the same number of triangles, they are just even longer.
6 triangles there.
and we extend the triangles to the next (and last) floor below.
we have again the same number of triangles, they are just very long.
6 triangles there.
that makes for the 4 floors
6Ă—4 = 24 triangles.