Ответ:

  1. \(6a+12=6(a+2)\);
  2. \(4x-8=4(x-2)\);
  3. \(5-15y=5(1-3y)\);
  4. \(10+5b=5(b+2)\);
  5. \(3-3c=3(1-c)\);
  6. \(2+6d=2(1+3d)\).