Correct use of Co or Jak when asking a question

I get confused when I try to ask a question. When is it correct to use Co and when is it correct to use Jak when you want to say "What" in a question. My example would be "Co Robisz" and "Jaki jest kolor naszego samochodu" Why do you use Co in one, but I can't say "Co jest kolor nasczego samochodu." What are the rules of when to use CO vs. JAK

I made a typo... I meant to say... "Why do you use Co in one, but I can't say "Co jest kolor nasszego samochodu." What are the rules of when to use CO vs. JAK" Przepraszam!

"Co" translates to "what".
"Jak" translates primarily to "how, which or what".
My answer may not cover all possibilities, but this is how I think of differences between "co" and "jak."

"Co Robisz?" = "What are you doing?"
"Czytam (coś)." = "I'm reading (something)."
In this case the answer includes an implied pronoun, a verb, with an implied object.
The answer could also be a noun if the question were different such as "Co to jest?" "What is it? "Radio."

"Jaki jest kolor samochodu?" = "What is the colour of the car?"
"Czerwony." = "Red."
In this case, you would give an answer with adjective such as "czerwony".
"Jak mowi po polsku?" = "How does he speak Polish?"
"Dobrze." = "(He speaks) Well."
In this case, you would give an answer with as adverb such as "well."

"Co jest kolor samochodu?" in this sentence doesn't sound natural. You expect the answer to be an adjective/something that defines the car, so you wouldn't use "co".

You may need to refer to a grammar book for a more thorough explanation.

Dzieki! Your explanation helps. If I understand you correctly, I should use "CO" when my answer would be a noun or a direct object (NOM, or ACC case) and JAKI when it would explain an ADJ like "jaki kolor jest naszego samochodu." I should use CO when I want a direct noun answer like "Co książka czytasz?" Czytam Animal Farm. I should ask "Jaki kolor jest naszego samochodu" when I want an answer with an ADJ like "nasz samochod jest bialy." Am I on the right track?

In the car example, you are on the right track.

Sort of... in the book example...
In the book example, you could ask
"Co czytasz? Czytam Animal Farm.
or
"Jaką książke czytasz? Czytam Animal Farm.
I guess another rule is that you would not use "co" right in front of a noun.

Sorry, maybe it might help if you think of "jak" and its variations as "how" or "which".
"What are you reading?" I'm reading Animal Farm. "CO"
"Which book are you reading?" "I'm reading Animal Farm. "JAK"

There is a twist though...
"Jaką książke czytasz?" "Czytam Animal Farm. could also be said like this
"Co za książke czytasz?" "Czytam Animal Farm." There is a word "za" between "co" and the "noun". I have heard this in colloquial language...

Sorry, I just noticed I made a typo...

In the book example such as "Jaką książkę czytasz?" There is a "ę" at the end of the książka word. It's not supposed to be an "e".

Also I don't know if the "Animal Farm" title undergoes modification at the end of the words due to cases. It an English title so it's not clear to me how it is treated in Polish sentences if it's an object.

I just thought I should mention this...

When you say "Jaką książke czytasz" Is that the ACC female case? Does Jak take the adj. female ACC ending and ksiazka take the ACC female noun ending for the direct object? What is the logic behind declining Jak into the ACC case? Because it answers the ACC question, WHAT? CO? Am I on the right track?

Also my question is: it's proper polish to say "Jaką książke czytasz" and "Co czytasz" but what exactly makes the distinction between Jak and Co. If I understand correctly is it a noun/direct object as an answer vs a Adj? Or is it a more like "which type of book are you reading vs What are you reading?"

I have a hard time translating english sentences into polish with the question of what (co/jak) and deciding whether to place a CO or JAK in front of the sentence.

Dzieki! Your clarification of "Jaką książkę czytasz" makes sense now since its the ACC female case of the direct object. Thank you for your help!!!

Another twist is that sometimes the questions themselves are different in English and Polish. For example, in English, we ask "What do you think?" In Polish, they ask "How do you think?" (Jak sądzisz?). "Co sądzisz would sound odd in this context.