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: Persoonia terminalis was first reported by Lawrie Johnson of the Royal Botanic Gardens, Sydney, Link Information: Lawrie Johnson, was an Australian taxonomic botanist. He worked at the Royal Botanic Gardens, Sydney, for the whole of his professional career, as a botanist (19481972), Director (19721985) and Honorary Research Associate (19861997) Question: How long had Johnson been working at the Gardens?
Answer: 33