Ответ:

  1. \(9(x+6)=72\Rightarrow x+6=8\Rightarrow x=2\).
  2. \(23(x-12)=552\Rightarrow x-12=24\Rightarrow x=36\).
  3. \(x+21x=1144\Rightarrow22x=1144\Rightarrow x=52\).
  4. \(15(2x+11)=285\Rightarrow2x+11=19\Rightarrow2x=8\Rightarrow x=4\).
  5. \(6y+11y+15=321\Rightarrow17y=306\Rightarrow y=18\).
  6. \(17x-8x-52=2711\Rightarrow9x=2763\Rightarrow x=307\).