Đáp án:
$x=3\\
y=6\\$
Giải thích các bước giải:
$2)
\dfrac{x}{3}=\dfrac{z}{10}\Rightarrow x=\dfrac{3z}{10}\\
\dfrac{y}{6}=\dfrac{z}{10}\Rightarrow y=\dfrac{6z}{10}\\
\Rightarrow x+z=7+y\\
\Leftrightarrow \dfrac{3z}{10}+z=7+\dfrac{6z}{10}\\
\Leftrightarrow \dfrac{3z}{10}+\dfrac{10z}{10}-\dfrac{6z}{10}=7\\
\Leftrightarrow \dfrac{7z}{10}=7\\
\Leftrightarrow z=7.\dfrac{10}{7}=10\\
\Rightarrow x=\dfrac{3.10}{10}=3\\
\Rightarrow y=\dfrac{6.10}{10}=6\\$