What is the origin of shorthand for "with" -> "w/"?

Is there a word for people who directly report to me in office? lsm99sky

• ที่ 18 ม.ค. พ.ศ. 2566 · CyberDefinitions gives a plausible explanation: Although its origin is contested, w/ has been used at least since the rise of the fast-food industry in the 1950s. As a form of shorthand to …
• ที่ 21 ธ.ค. พ.ศ. 2554 · In writing, when should one use the abbreviation vs. as opposed to the full versus? This abbreviation seems to have special status from common usage. What is the origin of that, and in …

Regarding Re: ; what is the correct usage in an email subject line? lsm99sky