P is True, q and r are False- find the truth value.
a) (p /\ ~q) /\ r

   (p /\ ~q) /\ r 
   (T /\ ~F) /\ F
   (T /\  T) /\ F
           T /\ T
             T   


b) ~(q ~ r)

That doesn't make sense, you left out a symbol.

If you left out /\, then  

   ~(q /\ ~r)
   
   ~(F /\ ~F)

   ~(F /\ T)

   ~F
   
    T

If you left out \/, then  

   ~(q \/ ~r)
   
   ~(F \/ ~F)

   ~(F \/ T)

   ~T
   
    F

Edwin