Boolean function to pin date range

Hello

I am struggling to create a formula to crack this (seemingly simple) nut.

I have two tables:

Table A contains user ID's and the date they attended training in sales techniques

Table B contains user ID, date, and number of sales

I would like to aggrigate the number of sales 2 days pre and two days post the date of their training.. the date of training being different for each person ID.

Ultimately, to get the the view of Average sales two days prior to training for everyone who was on training and the average sales for everyone to days after the training for everyone who attended training.

Help!