I have a spread sheet with for simplicity 4 columns
Column 1 is a Date Column,
Column 2 is a Company Name,
Column 3 is a Payment amount X
Column 4 is a Payment amount Y

The amount due is the sum of X+Y between the relevant dates.

The entries are in date order and the Company names random.
The number of entries per company varies also.
I want to be able to calculate the amount due for each company over a thee
month period between certain varied dates.

Questions
1. Is there a way to enter the dates to calculate between.
2. What is the best way to perform the calculations for each company?

An example or link to an example would be appreciated.
Regards
Dermot