Ответ:

  1. \(4x-6y+5y=4x-y\).
  2. \(7y-9y+2x+2y=2x\).
  3. \(y-2x-y+x=-x\).
  4. \(0.3y-0.1x-0.9x+0.7y=x-0.8y\).
  5. \(\frac15x-2.8y-0.2x+\frac45y=0-2y=-2y\).
  6. \(-\frac53y+1.5x+1.6y-0.5x=x-\frac1{15}y\).
  7. \(\frac13y-\frac13x+\frac13y+\frac13x+\frac13y=y\).