∀ {X : Type u_1} [inst : ConvexSpace ℝ X] [inst_1 : MetricSpace X] [IsConvexMetricSpace X] {s t : ℝ} (hs : 0 ≤ s)
  (ht : 0 ≤ t) (h : s + t = 1) (x y x' y' : X),
  dist (convexComboPair s t hs ht h x y) (convexComboPair s t hs ht h x' y') ≤ s * dist x x' + t * dist y y'