The distance from my house to school is a third of a mile.
Meaning: Jarak rumah saya ke sekolah sepertiga mil.

Jarak dari rumah saya ke sekolah adalah sepertiga mil.
= not accepted, reported.

"dari" = from.
This may be optional, but I don't think you can reject it.

"adalah" may be optional as well, but I don't think you can reject it.

If it's not valid, please explain.

I am confused when to use "adalah" and when "ada". I thought they were interchangeable, but these sentences are popping up from time to time when only one of them is accepted.