[ Eq(x20, Piecewise((0, Lt(t, -1)), (0, Lt(t, 0)), (1, Lt(t, 120)), (1, True))),
  Eq(x21, x20*k35),
  Eq(x22, x1),
  Eq(x23, x2),
  Eq(x24, x3),
  Eq(x25, x4),
  Eq(1*k51*x1 + 1*k51*x2 + 1*k51*x3 + 1*k51*x4 + 1*k51*x5 + 1*k51*x7 + 1*k51*x8 + 1*k52*x9 + 1*k52*x10 + 1*k52*x11 + 1*k52*x12 + 1*k52*x13 + 1*k52*x15 + 1*k52*x16 + 1*k52*x17, k51*k53 + k52*k54),
  Eq(1*k51*x6 + 1*k51*x7 + 1*k51*x8, k51*k55),
  Eq(1*k52*x14 + 1*k52*x15 + 1*k52*x16 + 1*k52*x17, k52*k56) ]