I've got this problem from my SAT Math level 2 prep book, which I think has the wrong answer.
The question is:
So what I did was subtract the matrix on the right by the left, and then both multiply both sides by -1.
The answer I get is
(-4 1 -11)
8 -1 -2
However in the book, the answer says b)
I have never done matrices before reading this book, and I'm trying to learn from the book. This is proving difficult as this book is quite hard to read, although I correctly answered the previous questions.