Extracting Number from various cell and added them and multiply with a factor

Sub

Public Sub CalcThis2()
    Dim inputDiap As Range, insp As Range, lube As Range, tigh As Range, repl As Range
    Dim fStr$, fStrOut$, lRow&
    
    With ActiveSheet
        lRow = .[A1].SpecialCells(xlLastCell).Row
        
        For i = 3 To lRow
            fStrOut = ""
            For Each iCell In .Cells(i, "I").Resize(1, 3)
                fStr = IIf(InStr(iCell.Text, "I") > 0, Replace(UCase(iCell.Text), "I", "*" & .Cells(i, "E").Text & "+"), UCase(iCell.Text))
        
                fStr = IIf(InStr(fStr, "L") > 0, Replace(fStr, "L", "*" & .Cells(i, "F").Text & "+"), fStr)
        
                fStr = IIf(InStr(fStr, "T") > 0, Replace(fStr, "T", "*" & .Cells(i, "G").Text & "+"), fStr)
        
                fStr = IIf(InStr(fStr, "R") > 0, Replace(fStr, "R", "*" & .Cells(i, "H").Text & "+"), fStr)
        
                fStrOut = fStrOut & fStr
            Next
            
            fStrOut = Replace(fStrOut, "+*", "+1*")
            Do While Right(fStrOut, 1) = "+"
                fStrOut = Left(fStrOut, Len(fStrOut) - 1)
            Loop
        
            Do While Left(fStrOut, 1) = "+" Or Left(fStrOut, 1) = "*"
                fStrOut = Mid(fStrOut, 2)
            Loop
            
            .Cells(i, "O") = Evaluate(Replace(fStrOut, ",", "."))   'Evaluate(fStrOut)
        Next i
    End With
End Sub

For example it will not always be 120I10L in cell I9, it can becomes 200I20L or even 100I20L2R, then will it be a problem?

No, it won`t be a problem

But I got Run-time error '13': Type mismatch on line : CalcThat = Evaluate(Replace(fStrOut, ",","."))

Then try to use

CalcThat = Evaluate(fStrOut)