Is RAM math possible in Conky?

I have process RAM, like a task manager, as one display & ramdisk usage like a LIVE boot as another:

Attachment 43373

Here are the entries:

Code:${mem} / ${memmax}Code:PS ${fs_used [ramdisk directory]} / ${fs_size [ramdisk directory]}I want a sum of the two figures.

tried:

Code:${mem + fs_used [ramdisk directory]}displays just mem

Code:${mem} + ${fs_used [ramdisk directory]}lists both figures separately but not a sum
Attached Thumbnails