∀ {R : Type u_3} {S : Type u_4} {A : Type u_1} {B : Type u_2} [inst : CommSemiring R] [inst_1 : Semiring A]
  [inst_2 : Algebra R A] [inst_3 : Semiring B] [inst_4 : Algebra R B] [inst_5 : CommSemiring S] [inst_6 : Algebra S A]
  [SMulCommClass R S A] (r : S) (x : TensorProduct R A B),
  (Algebra.TensorProduct.includeLeftRingHom.comp (algebraMap S A)) r * x =
    x * (Algebra.TensorProduct.includeLeftRingHom.comp (algebraMap S A)) r