rw [lt_eq_sub_lt_zero, @lt_eq_sub_lt_zero b₁, ← this hc₁, ← this hc₂, h]
a b c d a₁ a₂ b₁ b₂ c₁ c₂ : Int
hc₁ : c₁ > 0
hc₂ : c₂ > 0
h : c₁ * (a₁ - a₂) = c₂ * (b₁ - b₂)
this : ∀ {c x y : Int}, c > 0 → (c * (x - y) < 0) = (x - y < 0)
⊢ (a₁ < a₂) = (b₁ < b₂)
no goals