/sci/ - Science & Math

wanted to brush up on some 'basic' math and several anons told me to work through pic related
but on the VERY FIRST exercise set i was completely dumbfounded

>Justify each step using commutativity and associativity in proving the following identities. (a-b)+(c-d) = (a+c)+(-b-d)

what the fuck am i missing ? isnt the equation already solved and equal to something? where is the x? what am i supposed to do its all variables. Am i getting trolled ? im supposed to feel stupid now arent I. How the fuck is this even basic its not even a linear equation

i want to beat the fuck outta serg lang

>>14618617
Basic Mathematics by Serge Lang

Should I start with pic related?
or just get the khan academy from the appstore

>>12746028
I doubt moot would even manage this

I did it. I read the meme book cover to cover.

What's the opinion on this book? Or is there a better alternative to middle school /high school math? Looking back, I realized that I never paid attention in middle school and high school math and it has always been a sore spot for me.

>>12195678
>from scratch
other anons were recommending this?