Permutations and Combinations

Total points are 12 on the three sides of triangle of which 3 points are collinear on side PQ,

4 points are collinear on side QR, 5 points are collinear on side PR,

Hence total number of triangles formed

$$\begin{gathered} ={}^{12}C_3-{}^{3}C_3-{}^{4}C_3-{}^{5}C_3 \\ =220-1-4-10 \\ =205 \end{gathered}$$