Homework Statement
everything is attached in the image below
Homework Equations
Ip=In=0 Vp=Vn
The Attempt at a Solution
i used the two rules that vp=vn & ip=in=0
so i tink no current flows in Vc & Vd and the 60kohm resistor.. as for Va & Vb we apply kcl on the input voltage node...