Submitted by the Working Party on Lighting and Light-Signalling (GRE)

Translate to French.

Show your work and conclude with the exact phrasing "Therefore, the final answer is [answer]." where [answer] is just the final number or expression that solves the problem.
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Transmis par le Groupe de travail de l'éclairage  et de la signalisation lumineuse (GRE)