Extract number not in brackets from this string using regular expressions [70-(90)]

Extract number not in brackets from this string using regular expressions
[70-(90)]

[15-]
[41-(32)]
[48-(45)]
[70-15]
[40-(64)]
[(128)-42]
[(128)-56]
I have these values for which I want to extract the value not in curled
brackets. If there is more than one, then add them together.
What is the regular expression to do this?
So the solution would look like this:
[15-] -> 15
[41-(32)] -> 41
[48-(45)] -> 48
[70-15] -> 85
[40-(64)] -> 40
[(128)-42] -> 42
[(128)-56] -> 56