Question

a mass m2, sits on a table, m1. How close to the right edge can it be placed without tipping the table?

Answer 1

Here, we need to balance the torques and set them equal to zero. Obviously, as we need torque, we need lever arms too which you did not provide. You provided only mass.

so, if m1 is the mass of table and r1 is the lever arm (distance from the center of table to the point where mass m2 is or where the right leg is)

then we have

m1 * g * r1 - m2 * g * x = 0

solve for x, we get

x = m1 * g * r1 / m2 * g