\[\left\{ \begin{matrix}
7 \cdot (2x - 3) - 3 \cdot (4y - 3) = 20 \\
0,3x + 0,2y = 1,6\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ | \cdot 10 \\
\end{matrix} \right.\ \]
\[\left\{ \begin{matrix}
14x - 21 - 12y + 9 = 20 \\
3x + 2y = 16\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \\
\end{matrix} \right.\ \]
\[\left\{ \begin{matrix}
14x - 12y = 32\ \ \ \ \\
3x + 2y = 16\ \ | \cdot 6 \\
\end{matrix} \right.\ \Longrightarrow \left\{ \begin{matrix}
14x - 12y = 32 \\
18x + 12y = 96 \\
\end{matrix} \right.\ ( + )\]
\[32x = 128\]
\[x = 128\ :32\]
\[x = 4.\]
\[2y = 16 - 3x = 16 - 3 \cdot 4 = 16 - 12\]
\[2y = 4\]
\[y = 2.\]
\[\left\{ \begin{matrix}
x_{0} = 4 \\
y_{0} = 2 \\
\end{matrix} \right.\ \]
\[x_{0} - y_{0} = 4 - 2 = 2.\]
\[Ответ:2)\ 2.\]