1,x-5/x-4=4-2x/4-x
x-5=2x-4
x=4-5
x=-1
2,6x-1/3x+2=4x-7/2x-5
12x^2-13x-14=12x^2-32x+5
19x=19
x=1
3,(x/x-1)-(x-1/x-2)=(x-3/x-4)-(x-4/x-5)
(x^2-2x-x^2+2x-1)/(x-1)(x-2)=(x^2-8x+15-x^2+8x-16)/(x-4)(x-5)
(x-1)(x-2)=(x-4)(x-5)
x^2-3x+2=x^2-9x+20
6x=18
x=3