Delete content next to a word.

[Martinengo]

As you can see in this image: http://i.gyazo.com/8996a86cf19862e36838e56c3ebcc6c2.png

I want to delete all the text at the left of "lbs" and the word lbs as well, leaving only the (amount kg)

In case it's possible, I want to eliminate the parentesis, leaving only the "amount kg"

It's a really long list, so I just want to do it by replacing, but I don't know how to do it.

Thank you.