Manipulating variables (such as multiplying variable x2)

[L2V]

I've been having a tough time trying to find an answer to question about templating in vB3.8. Is it possible to manipulate a variable such as dividing or multiplying it? In my case, I want to take the standard avatar in postbit and divide the $post[avwidth] and $post[avheight] by 2 (so that the image is displayed as half the size). I know I can reduce the avatar size limit but that defeats the purpose of what I am trying to do. Is there a way to do $post[avwidth] / 2 or $post[avwidth] * .5 or something?