no goals
α : Type u_1
inst✝³ : AddGroup α
inst✝² : LinearOrder α
inst✝¹ : CovariantClass α α (fun x x_1 => x + x_1) fun x x_1 => x ≤ x_1
a b c : α
inst✝ : CovariantClass α α (swap fun x x_1 => x + x_1) fun x x_1 => x ≤ x_1
⊢ -a < b ∧ a < b ↔ -b < a ∧ a < b
rw [neg_lt]