Hi, please help me with this question...
How exactly do you come up with +15x and -12x? The textbook only tells that you multiply 10 and 18=180, and the sum of will be +15x and -12x. What's the point of coming up with 180? And how in the world.... what do you do to get 15x and -12x???
This is the same thing. How exactly do you come up with -10ab and 12ab to make -22ab?