find PD ::::

Let current in the loop AJ=I1 ,AND IN BI=I2 and direction as shown
Now consider the loop AJIB
We will get I1-1+1-I2=0 =>I1=I2
In the same way we can prove the current in the loops AJ,BI,CH,DG,EF are equal let it be I1
.we can also find tht current in BJ,CI,DH,EG are also equal ,and it b I2
Now current inGH=2I1-I2
In HI=3I1-2I2
In IJ=4I1-3I2
So in JB=5I1-3I2=I2
=>I2=5I1/4
Now in the loop ABJ
I1+I2=1
=>9I1/4=1
=>I1=4/9
I was taken points A of ur question as F in my soln
Hence Va-Vb=-31/9
iz the anser c orrect

ur ans is wrong !