Question

how do I answer Donde estudio Ud.?

Answer 1

Well it means "Where did you study?"

Answer 2

Yo estudio (place you study )

Answer 3

"Dónde estudió usted?"

That's the polite way of asking, "Where did you study?"

The question is in past tense.
So, we have to answer the question in past tense.

Start with "Yo estudié en"
It means "I studied in"

"Estudié" is the past tense, Yo form of "estudiar."
Do yourself a favor, memorize how to conjugate in the past tense.