1. The problem statement, all variables and given/known data everything is attached in the image below 2. Relevant equations Ip=In=0 Vp=Vn 3. 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 and solve for Vo current in Va is Ia and so forth.. and current in 375kohm(Re) resistor is Ie so Ia + Ib + Ie = 0 Va/Ra + Vb/Rb + Vo/Re = 0 so we calculate Vo from that for the second part we need to calculate the range for Vb so that -20<Vo<20 so i think we have to put Vo in terms of Vb and replace that in the range so that we get Vb can anyone help me with this??? it's late now and that's the best i can do..