To express the relationship between the weight of a ferret (y) and its length (x), you need a constant of proportionality, which we can denote as \( k \). Since the weight varies directly with the length, the relationship can be expressed as:
\[ y = kx \]
In this equation:
- \( y \) represents the weight of the ferret.
- \( x \) represents the length of the ferret.
- \( k \) is the constant of proportionality.
If you have a specific value for the weight and length of a ferret, you can calculate \( k \) by rearranging the equation:
\[ k = \frac{y}{x} \]
So, please provide a specific weight or length, or further details, if you want to calculate the constant of proportionality or complete the missing information.