[ Eq(1*k1*x1 + 1*k1*x3 + 1*k1*x6, k1*k9),
  Eq(1*k1*x2 + 1*k1*x3 + 1*k1*x6, k1*k10),
  Eq(1*k1*x4 + 1*k1*x5 + 1*k1*x6 + 1*k1*x7 + 1*k1*x8 + 1*k1*x9, k1*k11) ]