Clarification of Macro with saving roll

The following question is needed to clarify after both visiting the wiki and watching videos linked in it: I'm running a game using the FASA Trek engine, which mostly uses saving rolls against percentile dice.  I have had to add abilities to roll against every attribute and specific skill and am uncertain that I have properly set up the macros.  One example of what I have now is a basic "fire weapon" which looks like this: /me fires a phase pistol /roll 1d100 vs (@dexterity+@MarksMod)÷2 If anyone can offer any advice or needs further clarification before assisting, I appreciate whatever help anyone is able to give.

At a minimum, you probably want this: /me fires a phase pistol /roll 1d100 vs (@{dexterity}+@{MarksMod})÷2 If you want to see the total, you'd want something like: /me fires a phase pistol /roll 1d100 vs [[(@{dexterity}+@{MarksMod})/2]] If you want a full comparison: /me fires a phase pistol /roll 1d100>[[(@{dexterity}+@{MarksMod})/2]] (note that > in this context means greater than or equal to )

Thanks!  I've been running a test game to see how these work, so I'll run the variations in there.