"Sut dych chi wedi mynd?"
Translation:How have you gone?
It means 'how have you gone' in the context of how did you travel to wherever you went.
For a situation like an exam or an interview we would tend to ask 'How was the .....?
'Sut roedd yr arholiad?' - 'How was the exam?'
Sut roedd y cyfweliad? - 'How was the interview?'
Or we might ask 'How did you do' = 'Sut wnest ti?'