Problem adding cells with alpha characters

I have a form that I need to do and I am stuck with the format that it is in and I cannot seem to make it do what I need it to do!

I am attaching a sample of what I have and what it needs to do. Essentially it needs to add a series of cells across a row however the format is odd (S 6.5) as an example and it needs to skip cells where there is a weekend.
Any help would be tremendously appreciated!!