{ 1*k12*x3 + 1*k12*x17 + 1*k12*x33 = k12*k72,
  1*k12*x7 + 1*k12*x15 + 1*k12*x34 = k12*k73,
  1*k12*x11 + 1*k12*x16 + 1*k12*x27 + 1*k12*x32 = k12*k74,
  1*k12*x20 + 1*k12*x21 + 1*k12*x35 = k12*k75,
  1*k12*x25 + 1*k12*x26 + 1*k12*x27 = k12*k76,
  1*k13*x38 + 1*k13*x39 = k13*k77,
  1*k13*x40 + 1*k13*x41 = k13*k78 }