Since you're new and possibly not trolling, I'll try to summarize the objections you will meet:
-black trousers should not be worn with this jacket. Black odd trousers, should they be used at all, are an evening wear thing and a glen plaid odd jacket is not.
-grey trousers with grey glen plaid odd jacket is possible if the contrast in greys is big enough and the GP pattern is really well defined, but there are many ways to go wrong so it's likely a fail
- most GP looks like a suit instead of an odd jacket. Personally I have two GP odd jackets, but their patterns are really large, enough that I like them as odd jackets. Many GP odd jackets are not like this though. And I don't really end up wearing my two GP odd jackets that much.
- I can't imagine your grey GP odd jacket and khakis looking good.