Time management in chess

how do you manage your time during a game? when you are playing a slow time control like 45 45 60 5 how much time do you take per move?

The average game is 40 moves.  Divide total time by 40 then add the increment. That is your average time per move.  Complex situations will be 2-5 times as long, simple or forced situations will be much faster. 

However you must start somewhere and assuming 40 moves gives a basis for decision making.  If you leave it completely arbitrary you will most likely not manage time correctly, particularly if you are a beginner and don't know which moves require more thought.  The idea is that if you are using all of your resources (trying your best) then you will end the game with zero time on the clock. 

And of course you move very quickly if your still in "book"

I often work off the basis that if I have more time than my opponent then I can't lose on time.

For 40 moves in 2 hours, sudden death in 1 hour, I just try to keep to 3 minutes/move. Keep an eye on your time (I write down the time remaining, to the nearest minute, every move) and you'll be okay. You should know your openings to get to move 10 or so in a few minutes, and then you're ahead of schedule. I often make some moves in under a minute, and some tougher ones take closer to 7 minutes. I think assuming a 60 move game is a better idea than 40, because 60 is still somewhat common. You don't see as many 80 move games among amateurs because we blunder well before then.

Pick a time per move you want to maintain, and play a few games trying always to keep ahead of schedule. You'll find what works for you.