Formula for identifying start date and finish date and associated number of days

I have a number of activities within a project with each activity having a start date and a finish date.

What I would like is a function that looks at the 1st activity start date and the last activity finish date and convert this into the total amount of workdays taken to complete the project.

Attached is a spreadsheet with generic data. Column A references the project with the cells I am looking to use highlighted in yellow columns B and C.

Also I only need the dates, not the time so would like to know how to remove the time as well.
Thanks in advance
FBS

Thanks Ali. Works perfectly.

Work days would be NETWORKDAYS (Monday to Friday)

FBS

I struck a problem when I applied the formula. Not with the formula but with the data. It appears that the initial start date of the project may not necessarily be in the first row of the project and the final finish date in last row of the project.

Is there any way that the formula can search for the project (ref no column A) then the earliest date for the project in column B and the latest date for the project in column C?

Regards
FBS

Have provided updated spreadsheet which highlights the issue I have.

The projects highlighted in red text show where the earliest start date and the latest finish date are not necessarily in sequence as you run down the rows.

Hence the need for a formula to identify the earliest and latest dates per project randomly placed in associated project rows.

Thanks
FBS