Translation:Vanya, take a pen and write the answer quickly .
Is the Russian verb for 'to take' different from 'to get?' i.e., получить... I thought it was 'get a pen,' too.
'Fastly' is not a word. 'Fast' is both an adjective and an adverb. That said, I used 'quickly' in my response. Using fast as an adverb in an imperative statement seems more colloquial to me.