Assuming that these variables behave proportionally, we can solve this problem through proportional relationships:
[tex]\begin{gathered} \frac{300}{6}=\frac{x}{14} \\ x=\frac{300\times14}{6} \\ x=\frac{4200}{6} \\ x=700 \end{gathered}[/tex]She can drive 700 miles in 14 hours