[ Eq(1*k1*x1 + 1*k1*x2 + 1*k1*x5, k1*k6),
  Eq(1*k1*x2 + 1*k1*x3 + 1*k1*x5, k1*k7),
  Eq(1*k1*x4 + 1*k1*x5, k1*k8) ]