Question 742672
If you mean to write:
5-x/x-5
then its

5-1-5=-1 as long as x is not 0

But if you mean:


{{{
(5-x)/(x-5)

}}}

then we notice that 5-x and x-5 are opposite in value. therefore their quotient is -1:


{{{
(5-x)/(x-5)=((-1)*(-5+x))/(x-5)=((-1)*(x-5))/(x-5)=-1
}}}
(as long as x does not equal -5)




Also notice that is just a coincidence that both expressions have the same value

:)