Hi I am refering to proposition 2.14 in Atiyah-MacDonald introduction to commutative algebra and I cant 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!