Exercise 20: Defining Commands with an Optional Argument (Solution)

This is the solution to Exercise 20.

\documentclass[11pt]{scrartcl}

\newcommand*{\cost}[2][excl VAT @ 17.5\%]{\pounds#2 #1}

\begin{document}

Example 1 : \cost{50}

Example 2 : \cost{100}

Example 3 : \cost[inc VAT]{25}

Example 4 : \cost[]{75.60}

\end{document}