Question 313138
First, use this trick to make the 3-x term the same as the x-3 term:

-(3-x)=-3+x = x-3


So you can turn 3-x into x-3 if you put a negative sign in front of it:


4x(x-3) - 5(3-x)
4x(x-3) + 5(x-3)   [note I applied the trick here, which turned -5 into +5]
(4x+5)(x-3)