∀ {G : Type u_2} {H : Type u_3} [inst : MulOneClass G] [inst_1 : AddZeroClass H] (f : Additive G ≃+ H)
  (a : Multiplicative H),
  (AddEquiv.toMultiplicativeRight f).symm a = (AddMonoidHom.toMultiplicativeLeft f.symm.toAddMonoidHom) a