Detailed Instructions: 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'.
Q: Context: he kokubun-ji was first excavated in 1949, and is on a plateau above the Yoro River in close proximity to Tokyo Bay. Link Information: The is a river in Chiba Prefecture, Japan. It is 73.4 km in length Question: How long is the Yoro river?
A:
Answer: 73.4 km