{ 1*x1 + 1*x12 = k26,
  1*x3 + 1*x13 + 1*x14 + 1*x15 = k27,
  1*x4 + 1*x6 + 1*x13 + 1*x14 + 1*x15 = k28,
  1*x7 + 1*x9 = k29,
  1*x8 + 1*x10 = k30 }