I want to define a command to ease the font configuration as below:
The new command
\setfont takes two parameters: one is the size of the font, the other is the line space.
However, it is not convenient to specify the line spacing in point directly. The more intuitive way is to set, e.g. two line spacing, or 1.5 line spacing. So in my command I want to take the second parameter a scale factor. The problem is how to apply the scale factor to the line spacing arguments? With arithmetic operation or other workaround?