Factor 15x^2-24x+9 we know that we are supposed to divide by (3x-3) so that might be one of the factors (3x-3)(ax+y) a must be 5 since 5 times 3=15 (3x-3)(5x+y) y must be -3 because -3 times -3=9 so (3x-3)(5x-3) try to multiply and get 15x^2-15x-9x+9=15x^2-24x+9 true
now we have [(3x-3)(5x-3)]/(3x-3)=(3x-3)/(3x-3) times (5x-3)/1=1 times 5x-3 answer is 5x-3