Question

I need help with number 20. Please be sure to explain. Thank You! There is a picture attached btw.

Answer 1

He should have added 1 to both sides to make the -1 on the right go to 0.
Then it would be 0 + m = -16 + 1 = -15
You can check your work by adding -1 and -15, which does in fact equal -16.
Hope this helped :)