In this task, you're given a statement, further information available on a particular linked term from the statement, and a question. Your job is to generate the answer to the question by using the information provided. If there is no clear answer obtainable, output 'none'.

Context: His son William Frederick Havemeyer, retired from the sugar refining business in 1842 Link Information: William Frederick Havemeyer (February 12, 1804 – November 30, 1874)  Question: How old was William Havemeyer's son when he retired from the sugar refining business?
Answer: 38

Context: The broadnose sevengill shark (Notorynchus cepedianus) is known to prey on the crossback stingaree Link Information: It is recognizable because of its seven gill slits, while most shark species have five gill slits Question: What is the difference between the amount of gills the species known to prey on the crossback stingaree have compared to most shark species?
Answer: 2

Context: the Japanese government again dispatched Un'yō in September 1875 under the command of Inoue Yoshika to provoke a military response Link Information: none Question: How long did Yoshika command Un'yō?

Answer: none