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A triangle has side lengths of $(2.3 r-8.2 s)$ centimeters, $(7.6 r+2.8 t)$ centimeters, and $(1.5 t-2.5 s)$ centimeters. Which expression represents the perimeter, in centimeters, of the triangle?$\newline$$10.4 r t-s t-5.9 r s$$\newline$$9.9 r-10.7 s+4.3 t$$\newline$$9.9 r-6.7 s+0.3 t$$\newline$$11.4 r t-7.9 s t$