I have a couple of scss selectors where I use the same amount positive and negative, as in:
padding: 0 15px 15px; margin: 0 -15px 20px -15px;
A more sane solution according to sass guidelines would be to interpolate variables like the following example:
interpolate
margin: 0 -#{$pad} 20px -#{$pad};
An example: https://www.sassmeister.com/gist/c9c0208ada0eb1fdd63ae47830917293