+2448 
I put what I think each of these are but I only think that I got a few of them right.
+128408 15...if these are similar....we must have that
13/15 = 30/35
13/15 = 6/7 not true....so these are not similar
16.....if these were similar.....we must have that
40/60 = 23/34
2/3 = 23/34 ....not true.....so.....not similar
17 For these to be similar...we must have that
16/22 = 25 /33
8/11 = 26/33 .....not true....not similar
18 EFG similar to EBC
Angle E = Angle E and
EF / EG = EB/EC
50/60 = 20/24
5/6 = 5/6
19 Not similar
20 Not similar
+128408 One way for triangles to be similar is that we need that the ratios of the corresponding sides to be =
That is
short side of first triangle
_____________________ = A
short side of second triangle
Intermediate side of first triangle
__________________________ = B
Intermediate side of second triangle
Long side of first triangle
_______________________ = C
Long side of second triangle
So A = B = C for the triangles to be similar
So.....For 16 to be similar...we need that
23/40 = 34/55 = 36/60
23/40 = 34/55 = 3/5
None of these ratios are equal...so....not similar
For 17 to be similar....we need the sides around the equal angle need to be equal ratios
But
16/22 = 25/33 ???
8/11 = 25/33 these are not equal
For the same reason....the triangles in 19 aren't similar, either
In other words 14/9 not equal to 7/4
And the triangles in 20 are not similar because we can't establish any AA similarity
