Question 5·Medium·Linear Equations in Two Variables

A sporting-goods store sells baseball caps and knit hats. On a certain day, the store sold a total of 18 hats for a combined revenue of $258. The situation can be modeled by the system of equations

where $x$ is the number of baseball caps sold and $y$ is the number of knit hats sold.

Which statement is the best interpretation of $12$ in this context?