If [()/( ( ()/())abc)/ 3x-r] is equal to 3x−4, and bc is expressed as 5x−10, what is the value of abc?

A) 15x^2 - 38x + 24
B) 12x^2 - 28x + 16
C) 18x^2 - 48x + 30
D) 20x^2 - 50x + 32