∀ {R : Type u_2} {A : Type u_1} [inst : CommSemiring R] [inst_1 : CommSemiring A] [inst_2 : Algebra R A] (x y : R),
  (↑↑(Algebra.ofId R A).toRingHom).toFun (x + y) =
    (↑↑(Algebra.ofId R A).toRingHom).toFun x + (↑↑(Algebra.ofId R A).toRingHom).toFun y