x-4/x-5 -x-5/x-6=x-7/x-8 -x-8/x-9
1+1/x-5 -1-1/x-6=1+1/x-8 -1-1/x-9
1/x-5 -1/x-6=1/x-8 -1/x-9
-1/(x-5)(x-6)=-1/(x-8)(x-9)
(x-5)(x-6)=(x-8)(x-9)
x²-11x+30=x²-17x+72
6x=42
x=7
x-4/x-5 -x-5/x-6=x-7/x-8 -x-8/x-9
1+1/x-5 -1-1/x-6=1+1/x-8 -1-1/x-9
1/x-5 -1/x-6=1/x-8 -1/x-9
-1/(x-5)(x-6)=-1/(x-8)(x-9)
(x-5)(x-6)=(x-8)(x-9)
x²-11x+30=x²-17x+72
6x=42
x=7