Here is the situation:

Column A is a unique ID number
Column B is a $ amount
Column C to Column J has 7 monthly $ amounts

I would like to determine in how many months/days it would take for the sum
of the monthly amounts in Column C to J is equal to the $ amount in Column B.
(i.e. all of column C, D, E is 3 months)

If it is not to difficult to figure out days based on 30 day months and
percentages of the amount in given column. (i.e. all of column C half of
column D is 45 days)

Any advice and help is greatly appreciated.