i would like some help : stock of computer bought & sold

column C column d

1/1/05 6/1/05

3/1/05 4/1/05

7/1/05

9/1/05 10/1/05

10/1/05 11/01/05

12/01/05 15/1/05

i would like to calculate the number of days between a date(i specify each time) & the x(i specify how many each time) number of computer that have been here the longest period.

ex. i have sold 3 computers on 10/1/05. i want to calculate number of days 4 each 3 computers between 10/1/05 & ( column d isnot empty) the the oldest 3 computer in my stock

is it any clear?

i would appreciate any hlep

thank in advance

RB