答案：(a) $\$153$ (b) $\$150$
- 該玩具的售價
$\begin{array}{cl}
= & 255 \times (1-40\%) \\
= & \$ 153
\end{array}$ - 該玩具的成本
$\begin{array}{cl}
= & 153 \div (1 + 2\%) \\
= & \$150
\end{array}$
