First listen and then answer the question.
How long has Mr. Page been teaching?

    I have just received a letter from my old school, informing me that my former headmaster, Mr. Stuart Page, will be retiring next week. Pupils of the school, old and new, will be sending him a present to mark the occasion. All those who have contributed towards the gift will sign their names in a large album which will be sent to the headmaster's home. We shall all remember Mr. Page for his patience and understanding and for the kindly encouragement he gave us when we went so unwillingly to school. A great many former pupils will be attending a farewell dinner in his honour next Thursday. It is a curious coincidence that the day before his retirement, Mr. Page will have been teaching for a total of forty years. After he has retired, he will devote himself to gardening. For him, this will be an entirely new hobby. But this does not matter, for, as he has often remarked, one is never too old to learn.