Simplifying a rational expression

How do you simplify this: (x²  + 2x - 8) / (18 -7x -x²)?

x²  + 2x - 8
-------------
18 - 7x - x² 

x²  + 2x - 8
--------------   {switched bottom around}
-x²  - 7x + 18

x²  + 2x - 8
----------------   {factored -1 out of bottom}
-1(x²  + 7x - 18 )

(x + 4)(x - 2)
--------------   {factored top and bottom into two binomials}
-1(x + 9)(x - 2)

-(x + 4)
--------   {cancelled x - 2 on top and bottom}
(x + 9)

-x - 4
-------   {distributed negative sign}
x + 9

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