Answer :

You multiply the -1 by 4 as well giving you the answer 12x-4
IrisJung

The error she made is when she did distributive property, she did this:

4(3x) is 12x. That is correct.

Then she did this:

4(-1)= -1

that is the error. 4 times -1 is -4, not one. The actual answer is 12x-4

<Hope it helped!❤️~>