In this task, you're given a context, further information available on a particular linked term from the statement, and an answer term. Your job is to generate a question that can use the information provided to obtain the given answer. You should use the information on both context and link information to create the question. Note that the answer to the question should be exactly the given answer, and if the answer is none, the answer to the question shouldn't be obtainable from the context or linked information.

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) Answer: 33
How long had Johnson been working at the Gardens?