Balance the following equations in basic medium by ion-electron method and oxidation number method:

(a) Ion-electron method:
1. Write the oxidation and reduction half-reactions by observing the changes in oxidation numbers.
   Oxidation half-reaction.
            0               +1
           
Reduction half-reaction.
            0                -3
           
2. Balancing the oxidation half reaction.
 (i)Balancing P atoms by multiply  by 4
               
(ii) Add 4 electrons towards RHS to balance the charges. 
                 
(iii) Add 8OH^- towards LHS to balance the charges
              
         (Balanced oxidation half reaction)
3. Balancing the reduction half reaction
   (i) Balance P atoms by multiplying PH3 by 4
               0              -3
           
(ii) Add 12 electrons towards LHS  to balance the charge on P
             
(iii) Balance oxygen and hydrogen atoms by adding 12H2O towards LHS and 12OH- towards 
RHS

                                        [Balanced reduction half reaction]
4. Multiply balanced oxidation half-reaction by 3 and add it to the balanced reduction half-reaction, we have