[kuschku]

Could you please clarify how I should answer when people ask questions that I directly, and obviously answered already?

Especially when multiple – in this case 2 (!) – people ask the very same question, again and again.

Asking redundant questions is also discouraged in the guidelines.

[tomhoward]

Anything that can be said with an insulting implication (I.e., you are illiterate) can be said more effectively without the personal abuse.

When multiple people miss the point you're trying to make, it's safe to assume that you haven't made your point as clearly or convincingly as you'd hoped.

In which case it's perfectly fine to respond and further develop your point, but your point will carry much more weight if you're polite and respectful in the way you phrase it.