The system of equations are 7x+(n5)y+8=0 and 9x+(n+8)y+7=0. Find the value of \(n\) if the system of equations has a unique solution.
 
The equations have unique solution for all real numbers except \(n \neq\)
 
(Note: If the answer is a whole number mention as it is. If not round off the answer and submit as a whole number.)