Hi I am refering to proposition 2.14 in Atiyah-MacDonald introduction to commutative algebra and I can't find the bilinear maps that will induce $A$-module homomorphisms $f,g$ where $f:(M \oplus N) \otimes P \to (M \otimes P) \oplus (N \otimes P)$ , $ g :(M \otimes P) \oplus (N \otimes P) \to (M \oplus N) \otimes P $
and $f \circ g = id$ and $g \circ f = id $, hence $f$ and $g$ are isomorphisms.
Can anyone please help me?
Thanks!