Discussions of shop problems can often involve math that is expressed in algebraic notation. If you find that you have difficulty with such material, there's a good review of the fundamentals of notation here...

https://thirdspacelearning.com/gcse-...raic-notation/

It starts with the very simplest stuff and works its way up to a level comparable to that needed for material you might read here.



A somewhat more concise approach to notation can be found here...

https://www.shalom-education.com/cou...ng-like-terms/

but I would recommend that neophytes work through the first suggestion before attempting this expansion.