Help with Dates and Calculations

Hi - just wanted some tips to solve a problem I have.

I have:

1. Object with ID + dates + amount [produce]

2. Object with ID + Year of Planting [farms]

What I need to do is to be able to:

a. Graph or tabulate the Age of Palm vs Produce [ie use the produce data to group all the years produce, but instead of displaying by date I need age]

b. Another part would be to be able to compare the above with a standard value for the age of the plant

I can't seem to think of a solution - but I did get thanks to the forum to work out age of palm for farms!