Q:

Solve conditional equation with two variables, and one variable within a range

I have a simple equation s=n/r, knowing that s and n are between 0 and 1, and r>0, how do I find the values of n and s that make this equation true?
I am interested in proceeding in two ways. 
(i) Set a value for r and then find all n,s pairs that solve the equation
(ii) Find all values of r,s,n when the equation is true, always by keeping the constraints mentioned above

A:

The triplet $(r,n,s)$ is a solution of the equation with the other conditions iff
$$(r,n,s)\in (0,\infty)\times (0,\min(1,r))\times \{n/r\}$$

