[ Eq(1*x4 + 1*x10, k23),
  Eq(1*x5 + 1*x11, k24),
  Eq(1*x6 + 1*x12, k25),
  Eq(1*x8 + 1*x21 + 1*x22 + 1*x23 + 1*x24 + 1*x25 + 1*x39, k26) ]