In a plane 8 points are colliner out of 12 points, then the number of triangles we get with those 12 points is

For a triangle, we need 3 non-collinear points. So with 12 points (when all the 12 are such that any three non-collinear is $12C3$. But among them 8 points are collinear.

If all these 8 points are different we get  $8C3$ triangles as they are collinear.

In  $12C3$ triangles, we do not get  $8C3$ triangles

Therefore, The number of triangles we get = $12C3-8C3$ = 164