Question 412051
(S'U T')' 

<pre><font face = "consolas" color = "indigo" size = 4><b>

DeMorgan's Laws are:

1.     (A  &#5196;  B)' = A' &#5198;  B' 

and

2.     (A  &#5198;  B)' = A' &#5196;  B'

To do your problem we need the first one:

       (A  &#5196;  B)' = A' &#5198;  B'

Substitute (S') for A 
Substitute (T') for B
Substitute [ for (
Substitute ] for )


    [(S')  &#5196;  (T')]' 

        becomes

     (S')' &#5198;  (T')'


Substitute S for (S')' and T for (T')'

         S &#5198; T

Edwin</pre>