Ответ:

  1. \(2a+3a-(2+3)a-6a=5a-5a-6a=-6a\);
  2. \(4b+7b=11b\);
  3. \(5x-2x=3x\);
  4. \(6p-4p=2p\);
  5. \(9t+5t=14t\);
  6. \(3y+y-(3+1)y-9y=4y-4y-9y=-9y\);
  7. \(6c-c=5c\);
  8. \(2m-m=m\);
  9. \(n+3n=4n\);
  10. \(k+k=2k\);
  11. \(3x+6x+x=10x\);
  12. \(8e-e-2e=5e\);
  13. \(s+s+s-3s=0\);
  14. \(9a-5a+a=5a\);
  15. \(z+6z-3z=4z\).