How do you interpret/draw out the simplified circuits in Sedra's Microelectronics?

Question

I legitimately do not understand how the simplified drawings in this book are meant to be interpreted. Coming from a basic circuit analysis class which had everything explicitly drawn, I'm having a lot of trouble even interpreting the simplest circuits in this book and can't even get started with solving them.

Where do the arrows go? This notation is briefly addressed in chapter 1 where it says that the arrows are connected together, but that wouldn't make any sense, since I is given a different value in the problem.

Answer 1

It doesn't matter where the arrows go because they are separated from the circuit of interest by current sources.

For a more practical approach you may consider the arrows pointing up to a more positive supply while the arrows pointing down connect to a more negative supply. The important thing to realise is that 1 mA is coming from the top and I is departing to the bottom.