To find the slope of line \( h \), which is perpendicular to line \( g \), we first need to use the property that the slopes of two perpendicular lines are negative reciprocals of each other.
The slope of line \( g \) is given as \( \frac{7}{3} \).
To find the negative reciprocal, we follow these steps:
- Take the reciprocal of \( \frac{7}{3} \), which is \( \frac{3}{7} \).
- Then, change the sign to make it negative, which gives us \( -\frac{3}{7} \).
Thus, the slope of line \( h \) is
\[ \boxed{-\frac{3}{7}}. \]