(p-5)(p+2)   (p-5)(p+2)
---------- + ----------
(p-4)(p+4)   (4-p)(4+p)

(p-5)(p+2)(4-p)    (p-5)(p+2)(p-4)
--------------   + ---------------
(p-4)(p+4)(4-p)    (4-p)(4+p)(p-4)

(p-5)(p+2)(4-p) + (p-5)(p+2)(p-4)
---------------------------------
(p-4)(p+4)(4-p)

-p^3 + 7p^2 -2p - 40 + p^3 - 7p^2 +2p +40
-----------------------------------------------
-p^3 + 4p^2 + 16p - 64

0
----------------------
-p^3 + 4p^2 + 16p -64

0