total length vs moved length

[gotphish001]

Say I have a slab that is 10' x 10'. If I want to offset one side in so the total length is 8', I move that side in 2'. That gives me the 8'. Is there a way for me to put in the 8' which would be the end result instead of the amount I want to move the one side. In my example the numbers are simple and the math is simple. I'm asking for when I have something that is say 3'-4 1/16" and want the total to be like 2'-9 1/4". I want to just be able to type in the 2'-9 1/4". I shouldn't need to do the math in my head. I know there's got to be a way. My googling skills are failing me on this one.

[Eduardo Rolon]

If the direction is orthogonal you can use the "offset edge" place it on top of the opposite edge and type X if horizontal or Y if vertical, then 8' followed by + if moving to the right or -- (minus minus) if moving to the left. If you are in decimal or meters you only need one minus sign.

[gotphish001]

The double minus is what I was missing. If you only do one minus it sometimes works and sometimes doesn't. Every time I think I figured it out, I'd come to a minus situation and it would do something different.
Thanks

[Eduardo Rolon]

You can also do - +

[David Maudlin]

gotphish001 wrote:
The double minus is what I was missing. If you only do one minus it sometimes works and sometimes doesn't.

With imperial units, the first "-" will be seen as a separator between feet & inches, so the second "-" is read as the minus operator. If the Working Units are set to decimal feet or decimal inches, then the first "-" will be the operator (no feet & inches separator is needed).

David