18 because they need to be identical and you only have 18 chocolate bars
        
             
        
        
        
Zero depending on what axis it’s on
        
                    
             
        
        
        
Answer:
1,2,3 and 6 are similar triangles by AA similarity
Step-by-step explanation:
1) ∠DEC ≅ ∠FEG     {Vertically opposite angles}
DC //  GF
∠ECD ≅ ∠EGF     {Alternate interior angles}
∠EDC ≅ ∠EFG     {Alternate interior angles}
ΔDEC & ΔFEG are similar triangles by AA similarity
2)MN // QP
∠LQP ≅ ∠QMN   {Corresponding angles } 
∠LPQ ≅ ∠PNM   {Corresponding angles}
ΔLQP & ΔLMN are similar triangles by AA similarity
3) In ΔSYE ,
∠S = 180 - 90 - 39
∠S = 51°
In ΔCHW,
∠H = 180 - 51 - 90
∠H = 39
ΔSYE and ΔCHW
∠S ≅ ∠W = 51° 
∠Y ≅ ∠C = 90°
∠E ≅∠H = 39°
ΔSYE & ΔWCH are similar triangles by AA similarity
6) ∠P ≅ ∠Z      {Given}
∠PXQ ≅∠ZXY  {Vertically opposite angles}
ΔPXQ & ΔZXY are similar triangles by AA similarity