\left\{ \begin{array} { l } { 8 x + 2 y = 46 } \\ { 7 x + 3 y = 47 } \end{array} \right.

\left\{ \begin{array} { l } { 3 x = 24 } \\ { x + 3 y = 17 } \end{array} \right.

\left\{ \begin{array} { l } { x = 5y + 5 } \\ { 6 x - 4 y = 7 } \end{array} \right.

\left\{ \begin{array} { l } { x = y + 2z } \\ { 3 x - z = 7 } \\ { 3 z - y = 7 } \end{array} \right.

\left\{ \begin{array} { l } { a + b + c + d = 20 } \\ { 3a -2c = 3 } \\ { b + d = 6} \\ { c + b = 8 } \end{array} \right.