∀ {R : Type u_3} {A : Type u_2} {B : Type u_1} [inst : CommSemiring R] [inst_1 : Semiring A] [inst_2 : Semiring B]
  [inst_3 : Algebra R A] [inst_4 : Algebra R B] (f : A →ₐ[R] B) (r : R),
  (MulOpposite.op ∘ ⇑f) ((algebraMap R A) r) = (algebraMap R Bᵐᵒᵖ) r