Ответ:

  1. \(-6a-2-5a+3=-11a+1\).
  2. \(-0.4m+0.7+2-1m=-1.4m+2.7\).
  3. \(6n-(5n-(4n-3n+2))=6n-(5n-n-2)=2n+2\).
  4. \(2.7\cdot\frac49=1.2\), \(2.7\cdot\frac5{18}=0.75\). Значит, \(1.2-0.75y+y=1.2+0.25y\).