We will use the FOIL method to solve this.
(7x-7)(x+1)
Multiply 7x by x. Then, multiply 7x by 1. Then, multiply -7 by x. Then, Multiply -7 by 1.
[tex]7x^{2} + 7x - 7x -7[/tex]
Now, we need to simplify by combining like terms.
[tex]7x^{2} -7[/tex]
If you look, -7x and 7x are gone. This is because they cancel each other out.
I hope this helped and maybe consider giving me brainliest :)