In this figure counting the squares and we get the 27 squares.

in the above figure it consist 8 triangle so that no. of square is 3 so that total no. of triangle is 8 ✖ 3=24

and 4 triangle shown in question figure so that answer is 24+4=28 

The below figure shown the total no. of triangles is 8+8+2+6+4=28

First mark each rectangles 1, 2 and 3 after we can cube of 1 +8+27=36 we get the answer

3+3+3=9 triangle 

Triangle ABD +Triangle ADC =2

Same as 2+2+2=6

And Triangle ABC=1 

So that total no of triangle in this figure is 9+6+1=16