Can we do math with language

Yes.
Your two sentences are acceptable, but somewhat informal.

Both “plus” and “minus” are derived from Latin, meaning "more" and "less" respectively. Their use has been extended to many other meanings, more or less analogous. Plus also denotes positive; minus denotes negative.

The use of plus/minus has a notion of addition/subtraction in the following examples.

Four of us, plus my son’s girlfriend, went out to dinner.
(4 persons + 1 person = 5 persons; In fact, five of us went out to dinner.)

He was hurt in a drunken brawl outside the pub. He came home minus a couple of front teeth.
(minus = without)

Different meanings:

For this job, experience in SAS, SQL and R programming is definitely a big plus.

Some employers see a lack of relevant experience as a real minus.

題外:
The problem with so many tabloids is that it is aimed at the lowest common denominator in Hong Kong.

The computer nerds say there will be exponential growth in cloud computing in the near future.

Garlic 2010, I really don’t know if I answer your question correctly. If not, I'm afraid that's the pitiful sum of all my knowledge on this topic.

---One explanation is the non-defining clauses---
In all these two sentences the adjective clause could be omitted and the rest of sentence still make sense.The adjective clauses here after re-arrangement, are a kind of parenthesis, a casual remark, an explanation which can be written between brackets ,dashes,or commas.
What they do is to give additional information about an antecedent defined; called Non-defining or Amplifying clauses:-eg
I like the mild winter ,minus the rain, of Vancouver.
eg:-Your birthday present is a 2 week holiday, plus a companion, in Hawaii.

'Minus' and 'plus' can be used informally to mean 'without' and 'with' respectively, free from the mathematical meanings of subtraction and addition.

Math Use Bi
1=O====Obama
2=T==== Title
3=T==== Talking