∀ {A : Type u_1} (B : Type u_2) [inst : CommRing A] [inst_1 : CommRing B] [inst_2 : Algebra A B] (I : Ideal A)
  (x y : B ⧸ Ideal.map (algebraMap A B) I),
  (Algebra.TensorProduct.quotIdealMapEquivTensorQuotAux✝ B I) (x * y) =
    (Algebra.TensorProduct.quotIdealMapEquivTensorQuotAux✝¹ B I) x *
      (Algebra.TensorProduct.quotIdealMapEquivTensorQuotAux✝² B I) y