Inline calculations for row filter

Hi all,

I’m sure that this is an easy task but I can’t figure out how to filter rows relative to a flow variable.

Column is integer and I want to be able to filter between a flow variable value and that number -30 (always minus 30).

columnvalue between (flowvar - 30) and flow_var

I have run into this type of problem a couple of times and figured out with one node or another, but without a general approach and am still wrapping my head around the Knime logic