Let A = {a, b, c}, B = {d, e, f}, C = {g, h, k}, L = {b, c}, M= {d, e} and N = {g, k}.
verify that .
Let,
....(i)
Also,
.....(ii)
From (i) and (ii), we have
Also,
∴ ....(iii)
Conversely,
∴ ....(iv)
From (iii) and (iv), we have