Formula to calculate daily sales needed to reach a specific target

Hello everyone,

in the attached XLS link, you will find our achieved sales of this month per day and date. our sales peak is at it's highest from Sun to Thu. and we go down on Fri and start going back up on Sat.

https://onedrive.live.com/edit.aspx?...!133&app=Excel


what i'm hoping you can help me with is two things:

1- create a fourmla that can tell what is the needed sales number on each of the 3 time periods i mentioned above. Sun to thu, Fri and Sat. and to take into account past performance. for example, since we go down on Fri so the expected sales number should be lower than what we usually get from Sun to Thu. same goes fro Sat.

2- this formula should update it self automatically as each day goes by and calculate the new needed numbers to reach our final month target.

in the main work XLS, the sales number is auto populated. i just need something that can tell me the daily target needed based on ongoing performance.

Thanks.