I'm creating flat patterns for doors that we manufacture for compartments.  We have an equation the figure out the cut size by using the door opening side.  I was wondering if there was a way to create an equation where i could just put in the opening width of the compartment and it would give me the proper cut side for the door.  I created an equation as shown below

"D1@Sketch1" = "D1@Sketch1" + 4  Which i thought whatever value I added to D1@Sketch1 would add 4 inches, but there might be a glitch because it keeps adding 4 inches automatically, even if  i just open the sketch to edit it.  Also, when I turn it into a sheet metal base flange, it adds a wierd number.  I'm confused.  Maybe it can't be done, but I've worked with equations before, and this isn't that complicated.