[ Eq(1*x1 + 1*x12, k26),
  Eq(1*x3 + 1*x13 + 1*x14 + 1*x15, k27),
  Eq(1*x4 + 1*x6 + 1*x13 + 1*x14 + 1*x15, k28),
  Eq(1*x7 + 1*x9, k29),
  Eq(1*x8 + 1*x10, k30) ]