\(\text{Áp dụng tính chất dãy tỉ số bằng nhau.Ta có:}\\\dfrac{x}{3}=\dfrac{y}{6}=\dfrac{z}{5}=\dfrac{x-2y+3z}{3-2.6+3.5}=\dfrac{42}{6}=7.\\\Rightarrow \dfrac{x}{3}=7\Rightarrow x=7.3=21.\\\Rightarrow \dfrac{y}{6}=7\Rightarrow y=7.6=42.\\\Rightarrow \dfrac{z}{5}=7\Rightarrow 7.5=35.\\\Rightarrow T=x-y+z=21-42+35=14.\\\text{Vậy T=14.}\)
