a b : Int
h✝ : a < b
h : a + -b < b + -b
⊢ a - b < 0
a b : Int
h : a < b
⊢ a - b < 0
have h := Int.add_lt_add_right h (-b)
no goals
a b : Int
h✝ : a < b
h : a + -b < b + -b
⊢ a - b < 0
rwa [Int.add_right_neg] at h