Set $\displaystyle S/R$ be an extension of commutative rings, let $\displaystyle M$ be an $\displaystyle R$-module and let $\displaystyle N$ be an $\displaystyle S$-module. Show that there is a one-to-one correspondence between $\displaystyle Hom_{R}(N,M)$ and $\displaystyle Hom_{S}(N,Hom_{R}(S,M))$.