Question 25
(TUR 4) IMO4 Let $\mathbb Q^+$ be the set of positive rational numbers. Construct a function $f:\mathbb Q^+\to\mathbb Q^+$ such that
$$f(xf(y))=\frac{f(x)}y,$$
for all $x,y$ in $\mathbb Q^+$.
$$f(xf(y))=\frac{f(x)}y,$$
for all $x,y$ in $\mathbb Q^+$.