substitute in sum on range

[Luminary Xion]

=SUBSTITUTE(0&E8,",",".")-SUBSTITUTE(0&C8,",",".")
Okay, how can I do the same thing in the middle of this equation?
=SUM(OtherTab!C3:I3)

I need to substitute to change any , to . on C3:I3 for the math to work. Advice?

[Luminary Xion]

nvm; got my answer.

=SUMPRODUCT(SUBSTITUTE(0&OtherTab!C3:I3,",",".")+0 )