\[\left\{ \begin{matrix} \frac{1}{x} + \frac{2}{y + 1} = 3 \\ \frac{3}{x} + \frac{4}{y + 1} = 7\ \\ \end{matrix}\text{\ \ \ } \right.\ \]
\[\left\{ \begin{matrix} a + b = 3\ \ \ \ \ \\ 3a + 2b = 7 \\ \end{matrix} \right.\ \text{\ \ \ \ \ \ \ \ \ \ \ \ }\left\{ \begin{matrix} a = 3 - b\ \ \ \ \ \\ 3a + 2b = 7 \\ \end{matrix} \right.\ \]
\[3 \bullet (3 - b) + 2b = 7\]
\[9 - 3b + 2b = 7\]
\[- b = - 2\]
\[b = 2.\]
\[b = 2 \Longrightarrow a = 3 - 2 = 1.\]
\[\frac{1}{x} = 1 \Longrightarrow x = 1.\]
\[\frac{2}{y + 1} = 2\]
\[2 \bullet (y + 1) = 2\]
\[y + 1 = 1\]
\[y = 0\]
\[Ответ:(1;0).\]