Both your sentences use the impersonal passive form 'is said' which is always followed by an infinitive phrase. This is another way of writing 'they say that'. It is rather formal and is not usually used in conversation. In sentence 1) the correct answer is A) 'said to have studied' because the action of studying is in an unspecified period in the past and is talking about an experience in Robert's life. In the active the same sentence would be 'They say that Robert has studied abroad, but I don't know what country he studied in' 'to study' is not correct because if the action is present we would use 'said to be studying' but we know the action is completed in the past because of the use of past simple 'studied' in the second part of the sentence. 'to have been studying' is not correct because present perfect continuous does not denote completion. The correct answer in 2) could be either A) 'to have raised' if the old man no longer raises cattle (this means a past experience that lasted more than 30 years) or B) 'to have been raising cattle' if the old man still raises cattle today. In the active this sentence would be. 'They say the old man has been raising cattle for more than 30 years.' The present 'to raise' or 'to be raising' cannot be used because even if the old man still raises cattle, he started more than 30 years ago and in English we use present perfect tenses for actions that start in the past and continue to the present.

Robert is said to have studied abroad. Completed action here so the simple form is used. The old man is said to have been raising cattle for 30 years. "For 30 years" demands the continuous form. What do you mean "What is the difference?" The difference of what?