When to lay it down?

[SideCash]

Let's say you have $50. You raise preflop with AK to $5. 2 people call who have you covered. Flop comes A47. It is checked to you and you make a pot sized bet of $15... now there is $30 in the pot and you have $30 left in your stack. Is this an automatic call regardless of raise? How do you figure out when you should call, even when you feel you are beat, based purley on pots odds. Is there a formula?

[SideCash]

I'm probably not being clear. This is what I mean. These numbers are purley made up.

if I raise $5 preflop with AK and my stack is $15. Flop comes QT4. I bet $10, and oppenent pushes all in. Easy call right? Only $5 more bucks to call at a $25 pot.

But if I have $500 and raise $5 with AK. Same flop and same bet and someone with $500 moves all in on the flop easy laydown right?

But what about those gray areas. Say I had another $20 or $30 left in my stack when he pushes. Is there a formula of some sort that says when you should call, EVEN WHEN YOU THINK YOU ARE BEAT, just because you are pot commited. How do you calculate the close ones?