Corollary
Tag 061T, permanent. Cite it as [Bourbaki, Tag 061T].
Algebra, chapter III, § 5. Tensor algebra. Tensors
If is a projective -module, is a projective -module.
is a direct factor of a free -module (II, § 2, no. 2, Proposition 4) and hence is a direct factor of (no. 2); as is free (Theorem 1), this shows that is projective (II, § 2, no. 2).
Bourbaki puts the proof directly after the statement, so what is above is the statement and its proof together.