If you have a functioning MacBook already from 2015, I would get the iPad pro. Why not have the best of both worlds rather than having 2 extremely similar machines. I'm still using my MBP from 2012 and it works perfectly. I'm sure you have some years left on your 2015 model.
You guys already know about these books.
They are in mint condition: basically brand new.
Currently $250 on Amazon
$50 more, I can include all the workbooks
some schools are kind enough to actually post the implicit curve: see uoft's grading scheme, for example. my understanding is that other schools are similar . . .top 10% get A/A+, next 30 get B+ to A-, bottom 50 get Cs to Bs