The length, $y$, of a white whale was $162 \text{centimeters} \left(\text{cm}\right)$ when it was born and increased an average of $4.8 \text{cm}$ per month for the first $12$ months after it was born. Which equation best represents this situation, where $x$ is the number of months after the whale was born and $y$ is the length, in $\text{cm}$, of the whale?