答案：(a) $\$576$ (b) 潔儀
- 佩玲的日薪
$\begin{array}{cl}
= & \$480\times (1+20\%) \\
= & \$576
\end{array}$ - 潔儀的日薪
$\begin{array}{cl}
= & \$480\div(1-20\%) \\
= & \$600
\end{array}$$\because \$600 > \$576 > \$480$，
$\therefore $ 潔儀的日薪最高。
