{ 1*k20*x1 + 1*k20*x2 + 1*k20*x3 + 1*k20*x4 + 1*k20*x5 = k20*k21,
  1*k20*x6 + 1*k20*x7 = k20*k22,
  1*k20*x8 + 1*k20*x9 = k20*k23 }