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x in (-oo:+oo)
255 = (85*x)/3 // - (85*x)/3
255-((85*x)/3) = 0
(-85/3)*x+255 = 0
255-85/3*x = 0 // - 255
-85/3*x = -255 // : -85/3
x = -255/(-85/3)
x = 9
x = 9
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