Now to find out the net asset/(liability) I have seen that you have to add up all the assets - all liabilities. Is the net asset/(liability) the same as capital?

I am really confused right now as another way I have learnt is that u have fixed assets + (current assets - current liabilities) - long term liabilities = capital. This gives me the same answer as the equation above it, can someone clear this up for me thanks.

Ok sorry I understand now lol. Now I just want to know whether capital is the same as equity?

Depends on the use of the word capital and who you ask.

In accounting it can mean the same thing, as long as it's year-end and net income and drawings have been closed out. That is, the basic accounting equation is:
assets = liabilities + equity
For a sole proprietorship, everything comes down to a "capital" account, but for a corporation it wouldn't be called that as you'd have both stock and retained earnings and maybe treasury stock as well.

In finance, capital more means long-term debt and equity. (i.e. financing)

But the way you're using it, seems more like capital and equity could be used interchangibly.

However, I have some issues there. In your first set of equations (with the net assets/liabilities), the liabilities aren't negative. And "net assets" is the same as equity. And I don't like that second equation you used (which essentially is saying fixed assets plus working capital minus long-term debt - not sure where that's coming from), it's not technically right cause there's more assets than just fixed and current. There's also investments and intangibles.