Ответ:

  1. \(9x-7=21-5x\), \(14x=28\), \(x=2\).
  2. \(4(x-5)=x+4\), \(4x-20=x+4\), \(3x=24\), \(x=8\).
  3. \(8-5(8+3x)=13\), \(-32-15x=13\), \(-15x=45\), \(x=-3\).
  4. \(-5x=11-2(4x-2)\), \(-5x=15-8x\), \(3x=15\), \(x=5\).
  5. \((6x+5)-(8x+13)=3\), \(-2x-8=3\), \(-2x=11\), \(x=-\frac{11}{2}\).
  6. \(7-6(x+2)=3-5x\), \(-5-6x=3-5x\), \(-8=x\), \(x=-8\).