Ans: C
Let $\$x$ and $\$y$ be the marked price and the cost of the dictionary respectively. Hence, we have
Let $\$x$ and $\$y$ be the marked price and the cost of the dictionary respectively. Hence, we have
$\left\{ \begin{array}{ll}
x = y(1 + 30\%) & \ldots \unicode{x2460} \\
x(1- 20\%) = y + 5 & \ldots \unicode{x2461}
\end{array} \right. $
Sub. $\unicode{x2460}$ into $\unicode{x2461}$, we have
$\begin{array}{rcl}
y(1+30\%)(1-20\%) & = & y + 5 \\
1.04y – y & = & 5 \\
0.04y & = & 5 \\
y & = & 125
\end{array}$
Therefore, the cost of the dictionary is $\$125$.
