The equation of the line is given as:
\[ y = -\frac{5}{3}x + \frac{2}{3} \]
From this equation, we can identify the slope of the line, which is \(m = -\frac{5}{3}\).
Since line \(t\) is parallel to line \(s\), it will have the same slope. Therefore, the slope of line \(t\) is also:
\[ -\frac{5}{3} \]
Therefore, the slope of line \(t\) is \(-\frac{5}{3}\).