Choose any three by three square of dates on a calendar page...
After some matches were played, most of the information in the
table containing the results of the games was accidentally deleted.
What was the score in each match played?
Square numbers can be represented on the seven-clock (representing these numbers modulo 7). This works like the days of the week.
First you need to find the real profit for each tree type for
every 10 years.
Try looking at different combinations of years....
Is it best to grow three lots of trees for 30 years if you have
90 years to maximise your profit?
How about a spreadsheet?