Need help constructing this query in MS Access

Table A- Company ID, Balance, Invoice Date

Table B- Company ID, Revenue, Month(different format than invoice date), Year

Table C- Month(same format as table B), # of days in that month

What i need:
-Grouped by company ID,
-Expression: Balance/(Revenue/Number of days in the selected months)

My issue- - if i link months in table B and Table C, if a company shows up in only twice in a selected 3 month range, then it will only return 60 days in the formula. Where I need it to return all 3 months of days even if it isnt invoiced in one or two of those months. Also, if it is invoiced 3 or 4 times in one month, that month will be counted multiple times when counting the number of days