\(\frac{x}{2}=10\Leftrightarrow x=20\)
\(x+\frac{y}{3}=20+\frac{y}{3}=10\)\(\Leftrightarrow\frac{y}{3}=-10\Rightarrow y=-30\)
\(x+y+\frac{z}{5}=10\Leftrightarrow20+-30+\frac{z}{5}=10\)
\(\frac{z}{5}=20\Leftrightarrow z=100\)
Vậy \(x=20;y=-30;z=100\)
2. Để P là một số nguyên thì \(12⋮3n-1\)
\(3n-1\inƯ\left(12\right)\)
\(3n-1\in\left\{-12;-6;-4;-3;-2;-1;1;2;3;4;6;12\right\}\)
\(3n\in\left\{-11;-5;-3;-2;-1;0;2;3;4;5;7;13\right\}\)