Mabilis ang sagot mo sa tanong ko.

Because Filipino very often puts the predicate first.

In this sentence, mabilis is the predicate, and ang sagot mo sa tanong ko is the topic marked by ang.

So the structure is roughly:

• Mabilis = quick
• ang sagot mo sa tanong ko = your answer to my question

This predicate-first order is very natural in Filipino.

A more English-like order is also possible:

• Ang sagot mo sa tanong ko ay mabilis.

That is grammatical, but the version starting with Mabilis sounds more natural in everyday speech.

Ang is not exactly the English word the. It is a topic marker.

In ang sagot mo sa tanong ko, ang marks sagot mo sa tanong ko as the topic or highlighted noun phrase of the sentence.

So:

• ang sagot mo = your answer
• not simply the answer in a direct one-to-one English sense

Filipino uses markers like ang, ng, and sa to show a noun phrase’s role in the sentence.

There is no verb here, and that is completely normal in Filipino.

This is a verbless descriptive sentence. It works like:

• Mabilis = is quick
• ang sagot mo sa tanong ko = your answer to my question

So the sentence means something like:

• Your answer to my question is quick
• or more naturally, Your answer to my question was quick

Filipino often leaves out a verb like is in this kind of sentence.

Because Filipino commonly expresses possession with a noun followed by a short pronoun.

So:

• sagot mo = your answer
• tanong ko = my question

This is a very common pattern:

• bahay ko = my house
• kaibigan mo = your friend
• libro niya = his/her book

The pronouns here are:

• ko = my / me
• mo = your / you

In this sentence, they function as possessive pronouns.

Sa tanong ko means to my question.

Here:

• sa is a very common marker that can mean things like to, in, on, at, or for, depending on context
• tanong ko = my question

So:

• sagot mo sa tanong ko = your answer to my question

In this sentence, sa links the answer to the question it responds to.

Because mabilis ang sagot mo and mabilis na sagot mo do not have the same structure.

• Mabilis ang sagot mo = Your answer is quick.
• mabilis na sagot mo = your quick answer

The first is a full sentence. The second is just a noun phrase.

The word na is a linker used when an adjective directly modifies a noun:

• mabilis na sagot = quick answer
• magandang libro = good book

But in your sentence, mabilis is the predicate, not an adjective directly attached to sagot inside one noun phrase.

In this sentence, mabilis functions like an adjective because it describes sagot.

• Mabilis ang sagot mo = Your answer is quick.

But Filipino words like mabilis can often work in ways that cover both adjective-like and adverb-like meanings depending on the sentence.

For example:

• Mabilis ang kotse. = The car is fast.
• Mabilis siyang tumakbo. = He/She ran quickly.

So here it is best understood as describing the noun phrase ang sagot mo sa tanong ko.

Yes, absolutely.

That version is grammatical and means the same thing.

Compare:

• Mabilis ang sagot mo sa tanong ko.
• Ang sagot mo sa tanong ko ay mabilis.

The first is more natural in ordinary speech because predicate-first order is very common. The second can sound a bit more formal, careful, or emphatic.

The word ay is often used in this alternative sentence order, especially in more formal Filipino.

They are similar, but they focus on slightly different things.

• Mabilis ang sagot mo sa tanong ko.
  Focuses on your answer as a thing/result.
  Literally: Your answer to my question is quick.

• Mabilis kang sumagot sa tanong ko.
  Focuses on you answering the question quickly.
  Literally: You answered my question quickly.

In everyday English, both may translate similarly, but the Filipino structures highlight different parts of the situation.

Usually it means the answer was given quickly or was prompt.

So the idea is not normally that the answer itself was physically short in length. For that, Filipino would usually use a different word, such as:

• maikli = short

So:

• Mabilis ang sagot mo = Your answer was quick / You answered quickly
• Maikli ang sagot mo = Your answer was short

Context matters, but mabilis here normally refers to speed, not length.

Here, sagot is a noun meaning answer.

That is why it can take a possessor:

• sagot mo = your answer

Filipino also has verbal forms related to the same idea, such as:

• sumagot = to answer
• sagutin = to answer something/someone

So in this sentence:

• sagot = noun
• mabilis = predicate describing that noun phrase

Yes, if the context already makes it clear what question is being talked about.

You could say:

• Mabilis ang sagot mo. = Your answer is quick.

Adding sa tanong ko makes it more specific:

• Mabilis ang sagot mo sa tanong ko. = Your answer to my question is quick.

So the longer version is clearer and more explicit, but the shorter one is also natural if the listener already knows which question you mean.