(c)
$\left\lbrack \frac{2}{3} + \frac{r}{99} \right\rbrack = \left\{ \begin{array}{r}
0,\ \ \ \ \ \ \ \ r < 33 \\
1,\ \ r \geq 33
\end{array} \right.\$
$\therefore\ \ \ \ \sum_{r = 0}^{98}{\left\lbrack \frac{2}{3} + \frac{r}{99} \right\rbrack = \sum_{r = 0}^{32}\left\lbrack \frac{2}{3} + \frac{r}{99} \right\rbrack + \sum_{r = 33}^{98}\left\lbrack \frac{2}{3} + \frac{r}{99} \right\rbrack}$
$\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ = 0 + 66 = 66$