Question 824313
<pre>
1. T &#8835; G
2. S &#8835; G 
&#8756; (T &#8744; S) &#8835; G

(T &#8835; G) & (S &#8835; G)       given 
(~T &#8744; G) & (~S &#8744; G)     by  P &#8835; Q  <=> ~P &#8744; Q
(~T & ~S) &#8744; G           by &#8744; is distributive over &
~(T &#8744; S) &#8744; G            by deMorgan's law.
(T &#8744; S) &#8835; G             by  P &#8835; Q  <=> ~P &#8744; Q

Edwin</pre>