1. The problem states that there are 2 supervisors for every 18 baby unicorns. 2. We want to write an equation relating $n$, the number of supervisors, and $u$, the number of baby unicorns. 3. The ratio of supervisors to baby unicorns is given by $\frac{n}{u} = \frac{2}{18}$. 4. Simplify the fraction $\frac{2}{18}$ to $\frac{1}{9}$. 5. Therefore, the equation relating $n$ and $u$ is: $$n = \frac{1}{9} u$$ 6. This means for every 9 baby unicorns, there is 1 supervisor. 7. Since fractional supervisors are allowed, $n$ can be any real number satisfying this equation.