1. The problem statement, all variables and given/known data Let boundary = bdy, ∩ = intersection and C = contained. Show that the bdy (A) ∩ bdy(B) C bdy (A ∩ B). 2. Relevant equations 3. The attempt at a solution I can draw a diagram of this idea and visualize it my mind, but I cannot formally show this (this is second proof I've attempted). Can anyone help me get it started?