There is an absolutely wonderful moment in the movie Labyrinth, in which Jennifer Connelly’s character shouts out “That’s not fair”, to which David Bowie’s character replies, “You say that so often! I wonder what your basis for comparison is?”
That’s really what’s going on here, isn’t it? You find the grading policy unfair, apparently because it has impacted you negatively (or at least it hasn’t impacted you positively in the way it impacted your friend). However, you’ve given no real evidence for calling it unfair.
Also, even if you calculated things correctly and your friend ended up with an 88% as opposed to your 84%, and even if the threshold for an a is 90%, if there was a 2-percentage-point curve, guess what? Your friend gets an A, and you get a B. (Not saying that’s what happened, but it’s quite possible, and completely not unfair.)
Basically, it doesn’t matter if you think it’s right or not—all that depends at every institution of higher learning I’ve worked at is whether the instructor graded consistently and without showing favoritism to/discriminating against students capriciously. From what you have described, it appears that you do not have a case. Sure, you can fight it, but you’d be wasting your time, and expending effort that would be better used working on getting As in your classes for the coming semester.
(Oh—and by way of postscript, my teenage daughters use ‘salty’, and I’ve heard it used by the current college students I’m surrounded by. Please don’t mock people as out of touch for the slang they happen to use—it won’t improve the way people view you, and perhaps even more so if you’re wrong.)