1) 2am-2bm+2cm+3an-3bn+3cn=2m(a-b+c)+3n(a-b+c)=(a-b+c)(2m+3n)
2) 3mx+3nx+3kx-2my-2ny-2ky=3x(m+n+k)-2y(m+n+y)=(m+n+k)(3x-2y)
3) 7tx+7ty+7tz+4kx+4ky+4kz=7t(x+y+z)+4k(x+y+z)=(x+y+z)(7t+4k)
4) 11at+11ak+11ap-9bt-9bk-9pb=11a(t+k+p)-9b(t+k+p)=(t+k+p)(11a-9b)
