Question 571462
Multiply the numerator and denominator by -1  to make the first term positive, the result is 
{{{(x^2-10x+21)/(3x^2-23x+14)}}}
Factor the numerator and denominator, then cancel the common factors
{{{(x-3)(x-7)/(3x-2)(x-7)=(x-3)cross((x-7))/(3x-2)cross((x-7)) = (x-3)/(3x-2)}}}

Answer: {{{(x-3)/(3x-2)}}}