[ Eq(x3, k6*k22**k10/((k20*k8)**k10 + k22**k10)),
  Eq(x4, k7*k23**k11/((k20*k9)**k11 + k23**k11)),
  Eq(x5, k12*k22**k16/((k21*k14)**k16 + k22**k16)),
  Eq(x6, k13*k23**k17/((k21*k15)**k17 + k23**k17)) ]