Solve the system with the addition method: \[ \left\{\begin{array}{ll} -6 x+9 y= & 81 \\ +6 x+8 y= & 4 \end{array}\right. \] Answer: $(x, y)=$ Enter your answers as integers or as reduced fraction(s) in the form $A / B$.

Step 1 ：Add the two equations together to eliminate the variable x: -6x + 9y + 6x + 8y = 81 + 4, which simplifies to 17y = 85.

Step 2 ：Divide both sides of the equation by 17 to solve for y: y = 85 / 17, which simplifies to y = 5.

Step 3 ：Substitute y = 5 into the first equation to solve for x: -6x + 9(5) = 81, which simplifies to -6x = 36, and further simplifies to x = -6.

Step 4 ：The solution to the system of equations is x = -6 and y = 5. This means that these values of x and y satisfy both equations simultaneously.

Step 5 ：Final Answer: \( (x, y) = \boxed{(-6, 5)} \)