2(a-b)+a(a-b)=
7(x+y)-a(x+y)=
2(a-b)+c(b-a)=
2a(b-3)-5c(3-b)=


(m+1)-m(m+1)=
x(y-z)²+(z-y)²=
4(m+n)+(m+n)=
2(x-y)-a(x-y)=