Help with an Excel formula

Seaweedfarm 

Assuming that the colours have been applied directly, you'll need a custom VBA function:

Function SumByColor(DataRange As Range, ColorCell As Range) As Double
    Dim Cell As Range
    Dim Parts() As String
    Application.Volatile
    For Each Cell In DataRange
        If Cell.Interior.Color = ColorCell.Interior.Color Then
            Parts = Split(Cell.Value)
            On Error Resume Next
            SumByColor = SumByColor + Parts(1)
            On Error GoTo 0
        End If
    Next Cell
End Function

Use as in the screenshot:

The attached demo workbook is a macro-enabled workbook, so make sure that you allow macros when you open it.