∀ {F : Type u_2} {α : Type u_3} {β : Type u_4} [inst : FunLike F α β] [inst_1 : Group α] [inst_2 : Add β]
  [inst_3 : LE β] [MulLEAddHomClass F α β] (f : F) (a b c : α), f (a / c) ≤ f (a / b) + f (b / c)