Question 992121

How do I simplify this expression: (x-8)/(x-4)+(x-5)/(x-7)-2
using this method of simplifying: (a-4)/(a-5)-(a-5)/(a-6)= [1+ 1/(a-5)]-[1+ 1/(a-6)= 1/(a-5)-1/(a-6)= -1/[(a-5)(a-6)] 

Thank you
<pre>Simplifies to: {{{highlight_green((- 2x + 20)/((x - 4)(x - 7)))}}}, or {{{highlight_green((- 2x + 20)/(x^2 - 11x + 28))}}}