Đáp án:
\(\left\{ \begin{array}{l}
y = 30\\
x = 20\\
z = 42
\end{array} \right.\)
Giải thích các bước giải:
\(\begin{array}{l}
\left\{ \begin{array}{l}
3x = 2y\\
7y = 5z\\
x - y + z = 32
\end{array} \right.\\
\to \left\{ \begin{array}{l}
x = \dfrac{2}{3}y\\
z = \dfrac{7}{5}y\\
x - y + z = 32
\end{array} \right.\\
\to \left\{ \begin{array}{l}
\dfrac{2}{3}y - y + \dfrac{7}{5}y = 32\\
x = \dfrac{2}{3}y\\
z = \dfrac{7}{5}y
\end{array} \right.\\
\to \left\{ \begin{array}{l}
\dfrac{{16}}{{15}}y = 32\\
x = \dfrac{2}{3}y\\
z = \dfrac{7}{5}y
\end{array} \right.\\
\to \left\{ \begin{array}{l}
y = 30\\
x = 20\\
z = 42
\end{array} \right.
\end{array}\)
