=(3a-2)/(3a-4)(a-1)-(3a-4)/(3a-2)(a-1)
=[(3a-2)²-(3a-4)²]/(3a-2)(3a-4)(a-1)
=(3a-2+3a-4)(3a-2-3a+4)/(3a-2)(3a-4)(a-1)
=(6a-6)*2/(3a-2)(3a-4)(a-1)
=12(a-1)/(3a-2)(3a-4)(a-1)
=12/(3a-2)(3a-4)
=12/(9a²-18a+8)