Given: [tex] {x}^{2} - 7x + 7y - {y}^{2} [/tex]
Now factoring them,
[tex] = > (x - y)(x + y) - 7(x - y)[/tex]
[tex] = > (x - y)(x + y - 7)[/tex]
Therefore, the answer to the question is [tex] (x - y)(x + y - 7)[/tex]