I’ve clearly been listening to the BBC Today programme too much. This read like the start of one of their ‘puzzle for the day’ slots. 
I was expecting the next sentence to be something along the lines of:
“If I used all the bricks I have for this tree and I decide I want to make two trees the same size and another one two-thirds the size, how many bricks will I need and how many years will I have to wait if I don’t buy any more bricks and my wife gives me the same amount of bricks each year plus 15%?”
