Let A be a ring, x a cancellable element of A, M an A-module such that the homothety xM is injective, N an A-module annihilated by x, n an integer. The canonical homomorphisms of (A/xA)-modules
ExtA/xAn(M/xM,N)⟶ExtAn(M,N),
ExtAn(N,M)⟶ExtA/xAn−1(N,M/xM),
TornA(M,N)⟶TornA/xA(M/xM,N)
deduced from the exact sequences (4), (5) and (6) are isomorphisms.
Bourbaki puts the proof directly after the statement, so what is above is the statement and its proof together.