∀ {R : Type u_1} {M : Type u_2} {A : Type u_4} {B : Type u_5} [inst : CommSemiring R] [inst_1 : CommSemiring A]
  [inst_2 : CommSemiring B] [inst_3 : Algebra R A] [inst_4 : Algebra R B] [inst_5 : AddCommMonoid M] (m : M) (a : A)
  (b : B),
  (AddMonoidAlgebra.tensorEquiv R A B).symm (AddMonoidAlgebra.single m (a ⊗ₜ[R] b)) =
    a ⊗ₜ[R] AddMonoidAlgebra.single m b