c. $\left\{\begin{array}{l}2 x-y=23 \\ x-9=-1\end{array}\right.$

Step 1 ：Solve the second equation for x: \(x - 9 = -1 \Rightarrow x = 8\)

Step 2 ：Substitute x into the first equation: \(2(8) - y = 23 \Rightarrow y = -7\)

Step 3 ：\(\boxed{x = 8, y = -7}\)