oh, it means that Vout depends on A and how much supply voltage put in, so use KVL for the loop with supply voltage , we have the max value of Vout can reach, is that right? like this below
View attachment 339205

mr @MrChips is this correct?

 

Can you give a picture c about what you mean in the bold line?

No. I'm not going to spend a bunch of my time drawing 200 batteries.

Which part of the following pieces is tripping you up?

1) Put 200 1.5 V batteries in series.
Imagine them lying on their side, end to end, the negative terminal of each on the left, the positive terminals on the right.
2) Connect the negative terminal of the left-most battery to 0 V ground.
3) What is the voltage between the positive terminal of the right-most battery and ground?

 

No. I'm not going to spend a bunch of my time drawing 200 batteries.

Which part of the following pieces is tripping you up?

1) Put 200 1.5 V batteries in series.
Imagine them lying on their side, end to end, the negative terminal of each on the left, the positive terminals on the right.
2) Connect the negative terminal of the left-most battery to 0 V ground.
3) What is the voltage between the positive terminal of the right-most battery and ground?

No need upto 200 batts. Just a few is enough because the same naturally. It is not what you said, not correct.

 

So the voltage at the top is NOT 5 V, even though that point is connected directly to a 5 V source.

Think about that and now go back and look at where you drew the conclusion that Vn was 2 V because it happened to be connected directly to a 2 V source.