Typically failing the course, homework was 30% of your entire grade at my middle and high school.
Though 30% seems still pretty doable. I assume you need 50% total not to fail? You could get by without, (or more realistically by concentrating on doing a few pieces of homework with a high percent / effort ratio).
Scoring levels: 100-94: A 93-85: B 84-70: C 65-69: D 64-0: E
D is generally considered unsatisfactory, although you might be able to get away with 1 or 2 here or there.
In what sense? I mean, what happens if you get too many Ds? (Or even Fs?)