Ответ:

  1. \(x+y=5\Rightarrow y=5-x\).
  2. \(x-y=0\Rightarrow y=x\).
  3. \(y-x=-3\Rightarrow y=x-3\).
  4. \(x-3y=-6\Rightarrow -3y=-6-x\Rightarrow y=\frac{x+6}{3}=\frac13x+2\).
  5. \(-2x+y=3\Rightarrow y=2x+3\).
  6. \(x+5y=0\Rightarrow y=-\frac15x\).
  7. \(2y-3x=0\Rightarrow y=\frac32x\).
  8. \(5x+2y=-10\Rightarrow 2y=-10-5x\Rightarrow y=-\frac52x-5\).
  9. \(-4x-7y=5.6\Rightarrow -7y=5.6+4x\Rightarrow y=-\frac47x-0.8\).

Ответ: \(y=5-x;\ y=x;\ y=x-3;\ y=\frac13x+2;\ y=2x+3;\ y=-\frac15x;\ y=\frac32x;\ y=-\frac52x-5;\ y=-\frac47x-0.8\).