Formal:
* Straightforward: This implies simplicity and clarity.
* Obvious: This suggests that the answer is easily seen or understood.
* Self-evident: This implies the answer is clear without needing any explanation.
* Transparent: This suggests the answer is clear and easily understood.
* Uncomplicated: This implies the answer is simple and without any unnecessary complexity.
Informal:
* No-brainer: This implies the answer is very easy and obvious.
* Piece of cake: This implies the answer is very easy to find or understand.
* A breeze: This implies that the answer is easily and effortlessly found.
* Crystal clear: This suggests the answer is easily understood and without any confusion.
The best synonym to use will depend on the specific context of your sentence.