The question for the above circuit asks for the power developed by the 60 Volt power supply. The equations I've written to solve for this value are as follows:
At the super node consisting of V1/V3: (V1-60)/100 + (V1-60)/10 + (V3-V2)/20 + V3/400 -0.625Va = 0
At node V2: (V2-60)/5 - V2/200 + (V2-V3)/20 = 0
KVL around the loop consisting of V1, 175Iq and V3 V1 + 175Iq = V3
Conditional equations: Va = V2-60, Iq = V2/200
The correct answer is given as 1084 watts but so far no matter how I manipulate the above equations the best I can come up with is 1057 watts and that's by making some assumptions that don't agree at all with the polarities given in the schematic. Note: when I see an arrow pointing in the direction of current through a resistor, in this case Iq through R2, I treat it as a voltage drop with the arrow pointing in the direction of the drop...it that correct? (I'm basing all my calc's on conventional current flow.)
As a final note, this is a circuit question out of the 5th edition of 'Electric Circuits' by Nilsson and Riedel. I took a course some years ago (in 1998) that used this text book so I decided I'd see how much I've forgotten since then. Apparently it's quite a bit.