[tex]\displaystyle \Large \boldsymbol{} a) \ \underline{x^2-3x}+\underline{2x-6}-\underline{xy+3y}=\\\\\\x(x-3)+2(x-3)-y(x-3)=\boxed{(x-3)(x-y+2)} \\\\\\b) \ mn-mx-n+x=m(n-x)-(n-x) =\boxed{ (m-1)(n-x)}[/tex]
