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