For clearity, I would measure off the 19 yards for holding, then signal 1st down (#8); followed USC (#27) setting the stakes for 1/10. If mic'd , I would announce : "The play created a 1st down after the holding penalty. The USC penalty would then be enforced prior to reseting the stakes."
Respectfully disagree with the announcement, Ralph. (BTW, same result For NCAA.) And I'm not sure where you got penalizing 19 yards (maybe a "typo"?). The holding penalty would be 10 yards from the end of the run (A-40), taking the ball to the A-30. The 15-yard UNS would then take the ball to the A-15, first and ten.
"During the down, holding number 50, offense. That penalty leaves the ball beyond the line-to-gain, and results in first and ten for Bangor. After the down, unsportsmanlike conduct, number 50, Bangor. That penalty leaves the ball at the Bangor 15 yard line, first and ten, by rule. This is number 50's first unsportsmanlike conduct foul of the game."
I know we're, essentially, saying the same thing, in different ways. But, I think my announcement provides the 'masses' with more pertinent information. They don't know what "resetting the stakes" means, but they do understand "first and ten."
In my humble opinion, for what it's worth.
(Forgive me if Bangor was inappropriate, but I don't know any other Maine cities off the top of my head.)