Line passes through points and . Line is perpendicular to . What is the slope
of line ?
Simplify your answer and write it as a proper fraction, improper fraction, or integer.

### Step 1: Calculate the Slope of Line \( t \)
Given the points \( (10, 4) \) and \( (1, 2) \) on line \( t \), the slope \( m_t \) is given by:
\[
m_t = \frac{y_2 - y_1}{x_2 - x_1} = \frac{2 - 4}{1 - 10} = \frac{-2}{-9} = \frac{2}{9}.
\]

### Step 2: Determine the Slope of Line \( u \)
Line \( u \) is perpendicular to line \( t \). The slope \( m_u \) of line \( u \) is the negative reciprocal of \( m_t \):
\[
m_u = -\frac{1}{m_t} = -\frac{1}{\frac{2}{9}} = -\frac{9}{2}.
\]

### Final Answer
The slope of line \( u \) is:
\[
\boxed{-\frac{9}{2}}.
\]