Number of hours needed to clean the college

The graph plots the "Number of hours needed" against the "Number of cleaners". As the number of cleaners increases, the number of hours needed decreases, indicating an inverse relationship.

An inverse relationship can be represented by the formula $H = \frac{k}{C}$, where $H$ is the number of hours, $C$ is the number of cleaners, and $k$ is the constant of proportionality. From the graph, we can use the point where $C=1$ cleaner and $H=16$ hours.

Using the constant $k=16$, the equation describing the relationship between the number of hours needed ($H$) and the number of cleaners ($C$) is:

The relationship is an inverse proportion, and its equation is $\boxed{H = \frac{16}{C}}$.