Could you please check my response found at the following link : www(dot)jiskha.com/questions/1802395/How-do-we-test-the-validity-of-the-following-p-q-p-r-r-s-s-t

Answer 1

I don't like it.
p -> r
does not mean that ~p -> ~r
The converse is not always true.
All we know is that ~r -> ~p

From #1, we know that ~p is true, but we know nothing about what happens for ~p