How to use two pull down lists to pull information from a third table

Hi, can you help with a problem I'm having.

I have two pull down lists, one with 10 letter choices (A-I) and the other with the months of the year. So this obviously gives 120 possible choices. What I need is the user to choose one choice from each list and then, depending on what is chosen, a number of specific fields are then populated from given values in a separate table (which would either be on the same worksheet or on the second page, whatever is easier).

So below is a sample from the second table. A choice of "B" and "Apr", for example, would select the "6" (these figures are dates in that month). I then need this number to populate 3 specific fields in the first worksheet. Additionally I then need the display to add a given number, so the first box would show "6" plus 2, the second box would show that same 6 plus 5 and the third box would show the 6 plus 10. The 2, 5 and 10 are constant and will always be added to the number chosen.

....Jan.....Feb.....Mar.....Apr
A...3........4........3........4
B...6........7........5........6
D...8........9........8........8
E...11.....12......11......10
F...14.....15......14......12
__________________________

First page:
Choice: B
Choice: Apr

The dates chosen are:
[8] [11] [16]

__________________________
Choice: F
Choice: Mar

The dates chosen are:
[16] [19] [24]
__________________________

I hope this is clear. I have no idea how to achieve this. Can anyone help?