Solution
Triangles are:
Containing no triangles = A,B,C,D,E,F,G,H,I,J,K,L,M,N,O,P = 16
Containing 4 small triangles = ABCH, DJIK, EFGL, MHIJ, JKOL, MNOP , JCDE = 7
Containing 9 small triangles = MHIJABCDE, OJKLCDEFG, PMNOHIJKL = 3
Containing all triangles = 1
Total = 27