Suppose we have a triangle with mass M as shown:
Clearly, the normal force of from the system to the table is $Mg$.
But what if we added two blocks of equal mass m on sides BC and AC of triangle ABC? What would the normal force from the system (=triangle plus two blocks) to the table be then? (assuming all contact surfaces are frictionless, so the two blocks immediately start sliding off). Assume the triangle does not move on the surface it is on.
I believe the answer is $(2m+M)g$ but I am not sure if the two masses of mass $m$ that are sliding down the triangle affect the normal force in any way.